Expose otelcol_exporter_queue_batch_size metric

[iblancasa]

Description

Expose otelcol_exporter_queue_batch_size_bucket metric.

Link to tracking issue

Fixes #12894

Testing

• Added unit tests
• Manual test

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.43%. Comparing base (5af9b6f) to head (e752757).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13478      +/-   ##
==========================================
+ Coverage   91.40%   91.43%   +0.03%     
==========================================
  Files         641      641              
  Lines       42611    42674      +63     
==========================================
+ Hits        38947    39018      +71     
+ Misses       2842     2836       -6     
+ Partials      822      820       -2     

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[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[jmacd]

Note that #13582 fails its tests because presently it is missing the batch-size metric used in tests. It's really two things: (1) this PR is a requirement, (2) needing to rename from new otelcol_exporter_queue_batch_size metric to the old metric name.

[iblancasa]

@open-telemetry/collector-approvers do we need anything else to move forward with this?