[DOCS-13090] Add OP utilization metrics

[maycmlee]

What does this PR do? What is the motivation?

Merge instructions

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• Ready for merge

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Additional notes

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/may/add-op-comp-buffer-metrics/observability_pipelines/monitoring_and_troubleshooting/pipeline_usage_metrics

[bruceg]

This is an unfortunate choice of metric name, as it actually means the maximum buffer size in terms of number of events. It probably should have been max_size_events which would follow other standard metric naming conventions. I will ask the Vector team their thoughts about renaming this. It'll be a breaking change but we haven't really advertised this yet.

[bruceg]

Note that this followed the Vector buffer metric naming spec which contradicts the Vector metric naming spec

[maycmlee]

Ahh okay, that actually makes more sense. If you and Vector want to make the name change, let me know if you I should hold off publishing this.

Suggested change

	: Maximum event size for a source's buffer.
	: A source's maximum buffer size, defined as the number of events it can hold.

[bruceg]

WIP: enhancement(observability): Standardize buffer size metric names

[maycmlee]

Removed these metrics since the names are getting changed and released with 2.13 release:

• pipelines.source_buffer_max_event_size
• pipelines.transform_buffer_max_event_size

[maycmlee]

Thanks @bruceg! I followed up and made edits, could you confirm they look good or if they need further changes?

[maycmlee]

Ahh okay, that actually makes more sense. If you and Vector want to make the name change, let me know if you I should hold off publishing this.

Suggested change

	: Maximum event size for a source's buffer.
	: A source's maximum buffer size, defined as the number of events it can hold.

[iadjivon]

This can be addressed in a different PR, but visually, I wonder if it might be best to emulate the Buffer metrics (when buffering is enabled) format without mentioning
Metric, Description, and Available for

[maycmlee]

Hi @iadjivon! I don't quite understand. Are you saying to put the metric name as the header instead of Timed out request?