fix(sdk/trace): cache TracerMetrics on TracerProvider to prevent memory leak

[ravitheja4531-cell]

Description

Fixes #5016

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

All 230 existing SDK trace tests pass locally.

Does This PR Require a Contrib Repo Change?

• No.

Checklist

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[xrmx]

Thanks for the PR. I feel that instead of complicating the tracer we should probably make get_meter cheap instead. Now that the tracer is cached also this should be an issue anymore.

[ravitheja4531-cell]

Hi @xrmx ,
Thank you for the review and your suggestion. I understand your point about simplifying the approach by making "get_meter" more efficient instead of adding additional complexity. I will revisit the implementation and update the PR accordingly.

Also, I noticed there are merge conflicts in the current branch — I will resolve them and push the updated changes soon.

Please let me know if you have any additional suggestions in the meantime.

[xrmx]

@ravitheja4531-cell sdk's MeterProvider.get_meter is already using a cache so not sure there's much to do anymore. Also yesterday we've released a newer version with the cached tracer.

[xrmx]

Closing this, the added complexity does not make sense after #5007