[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/log/embedded/embedded.go

@@ -0,0 +1,36 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package embedded provides interfaces embedded within the [OpenTelemetry Logs
+// Bridge API].
+//
+// Implementers of the [OpenTelemetry Logs Bridge API] can embed the relevant
+// type from this package into their implementation directly. Doing so will
+// result in a compilation error for users when the [OpenTelemetry Logs Bridge
+// API] is extended (which is something that can happen without a major version
+// bump of the API package).
+//
+// [OpenTelemetry Logs Bridge API]: https://pkg.go.dev/go.opentelemetry.io/otel/log
+package embedded // import "go.opentelemetry.io/otel/log/embedded"
+
+// LoggerProvider is embedded in the [Logs Bridge API LoggerProvider].
+//
+// Embed this interface in your implementation of the [Logs Bridge API
+// LoggerProvider] if you want users to experience a compilation error,
+// signaling they need to update to your latest implementation, when the [Logs
+// Bridge API LoggerProvider] interface is extended (which is something that
+// can happen without a major version bump of the API package).
+//
+// [Logs Bridge API LoggerProvider]: https://pkg.go.dev/go.opentelemetry.io/otel/log#LoggerProvider
+type LoggerProvider interface{ loggerProvider() }
+
+// Logger is embedded in [Logs Bridge API Logger].
+//
+// Embed this interface in your implementation of the [Logs Bridge API Logger]
+// if you want users to experience a compilation error, signaling they need to
+// update to your latest implementation, when the [Logs Bridge API Logger]
+// interface is extended (which is something that can happen without a major
+// version bump of the API package).
+//
+// [Logs Bridge API Logger]: https://pkg.go.dev/go.opentelemetry.io/otel/log#Logger
+type Logger interface{ logger() }