[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/log/processor.go

@@ -0,0 +1,56 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package log // import "go.opentelemetry.io/otel/sdk/log"
+
+import (
+	"context"
+)
+
+// Processor handles the processing of log records.
+//
+// Any of the Processor's methods may be called concurrently with itself
+// or with other methods. It is the responsibility of the Processor to manage
+// this concurrency.
+//
+// See [FilterProcessor] for information about how a Processor can support filtering.
+type Processor interface {
+	// OnEmit is called when a Record is emitted.
+	//
+	// OnEmit will be called independent of Enabled. Implementations need to
+	// validate the arguments themselves before processing.
+	//
+	// Implementation should not interrupt the record processing
+	// if the context is canceled.
+	//
+	// All retry logic must be contained in this function. The SDK does not
+	// implement any retry logic. All errors returned by this function are
+	// considered unrecoverable and will be reported to a configured error
+	// Handler.
+	//
+	// The SDK invokes the processors sequentially in the same order as
+	// they were registered using WithProcessor.
+	// Implementations may synchronously modify the record so that the changes
+	// are visible in the next registered processor.
+	// Notice that Record is not concurrent safe. Therefore, asynchronous
+	// processing may cause race conditions. Use Record.Clone
+	// to create a copy that shares no state with the original.
+	OnEmit(ctx context.Context, record *Record) error
+
+	// Shutdown is called when the SDK shuts down. Any cleanup or release of
+	// resources held by the exporter should be done in this call.
+	//
+	// The deadline or cancellation of the passed context must be honored. An
+	// appropriate error should be returned in these situations.
+	//
+	// After Shutdown is called, calls to Export, Shutdown, or ForceFlush
+	// should perform no operation and return nil error.
+	Shutdown(ctx context.Context) error
+
+	// ForceFlush exports log records to the configured Exporter that have not yet
+	// been exported.
+	//
+	// The deadline or cancellation of the passed context must be honored. An
+	// appropriate error should be returned in these situations.
+	ForceFlush(ctx context.Context) error
+}