[chore] Simplify the OTEL setup (#4110)

# Description

This simplifies our OTEL setup by:

* Getting rid of some deprecated things.
* Using `autoexport` and letting things get configured by the `OTEL_` environment variables.
* Removing all the unnecessary config options.

## Checklist

Please put an x inside each checkbox to indicate that you've read and followed it: `[ ]` -> `[x]`

If this is a documentation change, only the first checkbox must be filled (you can delete the others if you want).

- [x] I/we have read the [GoToSocial contribution guidelines](https://codeberg.org/superseriousbusiness/gotosocial/src/branch/main/CONTRIBUTING.md).
- [x] I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
- [x] I/we have not leveraged AI to create the proposed changes.
- [x] I/we have performed a self-review of added code.
- [x] I/we have written code that is legible and maintainable by others.
- [ ] I/we have commented the added code, particularly in hard-to-understand areas.
- [x] I/we have made any necessary changes to documentation.
- [ ] I/we have added tests that cover new code.
- [x] I/we have run tests and they pass locally with the changes.
- [x] I/we have run `go fmt ./...` and `golangci-lint run`.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4110
Reviewed-by: tobi <kipvandenbos@noreply.codeberg.org>
Co-authored-by: Daenney <daenney@noreply.codeberg.org>
Co-committed-by: Daenney <daenney@noreply.codeberg.org>

vendor/go.opentelemetry.io/otel/sdk/trace/tracetest/README.md

@@ -0,0 +1,3 @@
+# SDK Trace test
+
+[![PkgGoDev](https://pkg.go.dev/badge/go.opentelemetry.io/otel/sdk/trace/tracetest)](https://pkg.go.dev/go.opentelemetry.io/otel/sdk/trace/tracetest)

vendor/go.opentelemetry.io/otel/sdk/trace/tracetest/exporter.go

@@ -0,0 +1,74 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package tracetest is a testing helper package for the SDK. User can
+// configure no-op or in-memory exporters to verify different SDK behaviors or
+// custom instrumentation.
+package tracetest // import "go.opentelemetry.io/otel/sdk/trace/tracetest"
+
+import (
+	"context"
+	"sync"
+
+	"go.opentelemetry.io/otel/sdk/trace"
+)
+
+var _ trace.SpanExporter = (*NoopExporter)(nil)
+
+// NewNoopExporter returns a new no-op exporter.
+func NewNoopExporter() *NoopExporter {
+	return new(NoopExporter)
+}
+
+// NoopExporter is an exporter that drops all received spans and performs no
+// action.
+type NoopExporter struct{}
+
+// ExportSpans handles export of spans by dropping them.
+func (nsb *NoopExporter) ExportSpans(context.Context, []trace.ReadOnlySpan) error { return nil }
+
+// Shutdown stops the exporter by doing nothing.
+func (nsb *NoopExporter) Shutdown(context.Context) error { return nil }
+
+var _ trace.SpanExporter = (*InMemoryExporter)(nil)
+
+// NewInMemoryExporter returns a new InMemoryExporter.
+func NewInMemoryExporter() *InMemoryExporter {
+	return new(InMemoryExporter)
+}
+
+// InMemoryExporter is an exporter that stores all received spans in-memory.
+type InMemoryExporter struct {
+	mu sync.Mutex
+	ss SpanStubs
+}
+
+// ExportSpans handles export of spans by storing them in memory.
+func (imsb *InMemoryExporter) ExportSpans(_ context.Context, spans []trace.ReadOnlySpan) error {
+	imsb.mu.Lock()
+	defer imsb.mu.Unlock()
+	imsb.ss = append(imsb.ss, SpanStubsFromReadOnlySpans(spans)...)
+	return nil
+}
+
+// Shutdown stops the exporter by clearing spans held in memory.
+func (imsb *InMemoryExporter) Shutdown(context.Context) error {
+	imsb.Reset()
+	return nil
+}
+
+// Reset the current in-memory storage.
+func (imsb *InMemoryExporter) Reset() {
+	imsb.mu.Lock()
+	defer imsb.mu.Unlock()
+	imsb.ss = nil
+}
+
+// GetSpans returns the current in-memory stored spans.
+func (imsb *InMemoryExporter) GetSpans() SpanStubs {
+	imsb.mu.Lock()
+	defer imsb.mu.Unlock()
+	ret := make(SpanStubs, len(imsb.ss))
+	copy(ret, imsb.ss)
+	return ret
+}

vendor/go.opentelemetry.io/otel/sdk/trace/tracetest/recorder.go

@@ -0,0 +1,94 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package tracetest // import "go.opentelemetry.io/otel/sdk/trace/tracetest"
+
+import (
+	"context"
+	"sync"
+
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+)
+
+// SpanRecorder records started and ended spans.
+type SpanRecorder struct {
+	startedMu sync.RWMutex
+	started   []sdktrace.ReadWriteSpan
+
+	endedMu sync.RWMutex
+	ended   []sdktrace.ReadOnlySpan
+}
+
+var _ sdktrace.SpanProcessor = (*SpanRecorder)(nil)
+
+// NewSpanRecorder returns a new initialized SpanRecorder.
+func NewSpanRecorder() *SpanRecorder {
+	return new(SpanRecorder)
+}
+
+// OnStart records started spans.
+//
+// This method is safe to be called concurrently.
+func (sr *SpanRecorder) OnStart(_ context.Context, s sdktrace.ReadWriteSpan) {
+	sr.startedMu.Lock()
+	defer sr.startedMu.Unlock()
+	sr.started = append(sr.started, s)
+}
+
+// OnEnd records completed spans.
+//
+// This method is safe to be called concurrently.
+func (sr *SpanRecorder) OnEnd(s sdktrace.ReadOnlySpan) {
+	sr.endedMu.Lock()
+	defer sr.endedMu.Unlock()
+	sr.ended = append(sr.ended, s)
+}
+
+// Shutdown does nothing.
+//
+// This method is safe to be called concurrently.
+func (sr *SpanRecorder) Shutdown(context.Context) error {
+	return nil
+}
+
+// ForceFlush does nothing.
+//
+// This method is safe to be called concurrently.
+func (sr *SpanRecorder) ForceFlush(context.Context) error {
+	return nil
+}
+
+// Started returns a copy of all started spans that have been recorded.
+//
+// This method is safe to be called concurrently.
+func (sr *SpanRecorder) Started() []sdktrace.ReadWriteSpan {
+	sr.startedMu.RLock()
+	defer sr.startedMu.RUnlock()
+	dst := make([]sdktrace.ReadWriteSpan, len(sr.started))
+	copy(dst, sr.started)
+	return dst
+}
+
+// Reset clears the recorded spans.
+//
+// This method is safe to be called concurrently.
+func (sr *SpanRecorder) Reset() {
+	sr.startedMu.Lock()
+	sr.endedMu.Lock()
+	defer sr.startedMu.Unlock()
+	defer sr.endedMu.Unlock()
+
+	sr.started = nil
+	sr.ended = nil
+}
+
+// Ended returns a copy of all ended spans that have been recorded.
+//
+// This method is safe to be called concurrently.
+func (sr *SpanRecorder) Ended() []sdktrace.ReadOnlySpan {
+	sr.endedMu.RLock()
+	defer sr.endedMu.RUnlock()
+	dst := make([]sdktrace.ReadOnlySpan, len(sr.ended))
+	copy(dst, sr.ended)
+	return dst
+}

vendor/go.opentelemetry.io/otel/sdk/trace/tracetest/span.go

@@ -0,0 +1,166 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package tracetest // import "go.opentelemetry.io/otel/sdk/trace/tracetest"
+
+import (
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	tracesdk "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// SpanStubs is a slice of SpanStub use for testing an SDK.
+type SpanStubs []SpanStub
+
+// SpanStubsFromReadOnlySpans returns SpanStubs populated from ro.
+func SpanStubsFromReadOnlySpans(ro []tracesdk.ReadOnlySpan) SpanStubs {
+	if len(ro) == 0 {
+		return nil
+	}
+
+	s := make(SpanStubs, 0, len(ro))
+	for _, r := range ro {
+		s = append(s, SpanStubFromReadOnlySpan(r))
+	}
+
+	return s
+}
+
+// Snapshots returns s as a slice of ReadOnlySpans.
+func (s SpanStubs) Snapshots() []tracesdk.ReadOnlySpan {
+	if len(s) == 0 {
+		return nil
+	}
+
+	ro := make([]tracesdk.ReadOnlySpan, len(s))
+	for i := 0; i < len(s); i++ {
+		ro[i] = s[i].Snapshot()
+	}
+	return ro
+}
+
+// SpanStub is a stand-in for a Span.
+type SpanStub struct {
+	Name                 string
+	SpanContext          trace.SpanContext
+	Parent               trace.SpanContext
+	SpanKind             trace.SpanKind
+	StartTime            time.Time
+	EndTime              time.Time
+	Attributes           []attribute.KeyValue
+	Events               []tracesdk.Event
+	Links                []tracesdk.Link
+	Status               tracesdk.Status
+	DroppedAttributes    int
+	DroppedEvents        int
+	DroppedLinks         int
+	ChildSpanCount       int
+	Resource             *resource.Resource
+	InstrumentationScope instrumentation.Scope
+
+	// Deprecated: use InstrumentationScope instead.
+	InstrumentationLibrary instrumentation.Library //nolint:staticcheck // This method needs to be define for backwards compatibility
+}
+
+// SpanStubFromReadOnlySpan returns a SpanStub populated from ro.
+func SpanStubFromReadOnlySpan(ro tracesdk.ReadOnlySpan) SpanStub {
+	if ro == nil {
+		return SpanStub{}
+	}
+
+	return SpanStub{
+		Name:                   ro.Name(),
+		SpanContext:            ro.SpanContext(),
+		Parent:                 ro.Parent(),
+		SpanKind:               ro.SpanKind(),
+		StartTime:              ro.StartTime(),
+		EndTime:                ro.EndTime(),
+		Attributes:             ro.Attributes(),
+		Events:                 ro.Events(),
+		Links:                  ro.Links(),
+		Status:                 ro.Status(),
+		DroppedAttributes:      ro.DroppedAttributes(),
+		DroppedEvents:          ro.DroppedEvents(),
+		DroppedLinks:           ro.DroppedLinks(),
+		ChildSpanCount:         ro.ChildSpanCount(),
+		Resource:               ro.Resource(),
+		InstrumentationScope:   ro.InstrumentationScope(),
+		InstrumentationLibrary: ro.InstrumentationScope(),
+	}
+}
+
+// Snapshot returns a read-only copy of the SpanStub.
+func (s SpanStub) Snapshot() tracesdk.ReadOnlySpan {
+	scopeOrLibrary := s.InstrumentationScope
+	if scopeOrLibrary.Name == "" && scopeOrLibrary.Version == "" && scopeOrLibrary.SchemaURL == "" {
+		scopeOrLibrary = s.InstrumentationLibrary
+	}
+
+	return spanSnapshot{
+		name:                 s.Name,
+		spanContext:          s.SpanContext,
+		parent:               s.Parent,
+		spanKind:             s.SpanKind,
+		startTime:            s.StartTime,
+		endTime:              s.EndTime,
+		attributes:           s.Attributes,
+		events:               s.Events,
+		links:                s.Links,
+		status:               s.Status,
+		droppedAttributes:    s.DroppedAttributes,
+		droppedEvents:        s.DroppedEvents,
+		droppedLinks:         s.DroppedLinks,
+		childSpanCount:       s.ChildSpanCount,
+		resource:             s.Resource,
+		instrumentationScope: scopeOrLibrary,
+	}
+}
+
+type spanSnapshot struct {
+	// Embed the interface to implement the private method.
+	tracesdk.ReadOnlySpan
+
+	name                 string
+	spanContext          trace.SpanContext
+	parent               trace.SpanContext
+	spanKind             trace.SpanKind
+	startTime            time.Time
+	endTime              time.Time
+	attributes           []attribute.KeyValue
+	events               []tracesdk.Event
+	links                []tracesdk.Link
+	status               tracesdk.Status
+	droppedAttributes    int
+	droppedEvents        int
+	droppedLinks         int
+	childSpanCount       int
+	resource             *resource.Resource
+	instrumentationScope instrumentation.Scope
+}
+
+func (s spanSnapshot) Name() string                     { return s.name }
+func (s spanSnapshot) SpanContext() trace.SpanContext   { return s.spanContext }
+func (s spanSnapshot) Parent() trace.SpanContext        { return s.parent }
+func (s spanSnapshot) SpanKind() trace.SpanKind         { return s.spanKind }
+func (s spanSnapshot) StartTime() time.Time             { return s.startTime }
+func (s spanSnapshot) EndTime() time.Time               { return s.endTime }
+func (s spanSnapshot) Attributes() []attribute.KeyValue { return s.attributes }
+func (s spanSnapshot) Links() []tracesdk.Link           { return s.links }
+func (s spanSnapshot) Events() []tracesdk.Event         { return s.events }
+func (s spanSnapshot) Status() tracesdk.Status          { return s.status }
+func (s spanSnapshot) DroppedAttributes() int           { return s.droppedAttributes }
+func (s spanSnapshot) DroppedLinks() int                { return s.droppedLinks }
+func (s spanSnapshot) DroppedEvents() int               { return s.droppedEvents }
+func (s spanSnapshot) ChildSpanCount() int              { return s.childSpanCount }
+func (s spanSnapshot) Resource() *resource.Resource     { return s.resource }
+func (s spanSnapshot) InstrumentationScope() instrumentation.Scope {
+	return s.instrumentationScope
+}
+
+func (s spanSnapshot) InstrumentationLibrary() instrumentation.Library { //nolint:staticcheck // This method needs to be define for backwards compatibility
+	return s.instrumentationScope
+}