Improved OpenTelemetry OTLP error handling

[nuclearpidgeon]

Updates to the OpenTelemetry input plugin's HTTP/2 server code to handle/report error cases better.

These were changes I made as part of other work trying to fix #8734 - but I have split them out into a separate PR as I can imagine they may need to be reviewed separately.

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Testing requirements

• Example configuration file for the change:

service:
    log_level: debug
pipeline:
    inputs:
        - name: opentelemetry
          tag_from_uri: true
          http2: true
    outputs:
        - name: 'stdout'
          match: '*'

• Debug log output from testing the change (will add in update)

• Attached Valgrind output that shows no leaks or memory corruption was found

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• Run local packaging test showing all targets (including any new ones) build.
• Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• Documentation required for this feature - don't think so? Although the new HTTP 400 case might warrant documenting.

Backporting

• Backport to latest stable release.

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[cosmo0920]

The contents of patch looks good. But we need to handle CI complains which is from commit messages.

Could you use in_opentelemetry: prefix in your commit messages?

[edsiper]

commits were squashed and commit fixed.

[nuclearpidgeon]

Somehow missed emails about this the other week. Thanks for cleaning up the commits. Will use the right prefix moving forwards :-)