fix(components): count bytes received for OTLP gRPC exports

[gyubin02]

Summary

Fixes missing component_bytes_received_total accounting for OTLP gRPC requests.

The HTTP path was already incrementing bytes_received, but the shared gRPC OTLP path was not. This change updates
the gRPC metrics, logs, and traces export() handlers to increment the counter using the serialized protobuf payload
size.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

How did you test this PR?

• Added regression tests for OTLP gRPC metrics/logs/traces exports to verify that component_bytes_received_total is
  incremented.
• Ran:
  • cargo test -p saluki-components updates_bytes_received

References

• Closes: OTLP source doesn't properly emit component_bytes_received_total. #1245

[tobz]

Awesome. Thanks for your contribution. :)

[gyubin02]

Thanks for the approval. The required dd-gitlab checks are still stuck in "Expected" on GitHub, so the PR can't merge yet. Could you please trigger or rerun the GitLab CI for this PR?

[tobz]

Thanks for the approval. The required dd-gitlab checks are still stuck in "Expected" on GitHub, so the PR can't merge yet. Could you please trigger or rerun the GitLab CI for this PR?

Yeah, that's weird. I'll try giving those a kick to get things moving again.

[tobz]

@gyubin02 Alright, got CI to run and things look good.

Last step is just to sign our CLA. We don't have the CLA bot set up yet (yay, you're our first external contribution! 🎉) so I'm pasting it here manually.

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

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I have read the CLA Document and I hereby sign the CLA

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[gyubin02]

I have read the CLA Document and I hereby sign the CLA