fix(sdk-logs): Fix Not Exporting Upon _maxExportBatchSize

[JacksonWeber]

Which problem is this PR solving?

This pull request addresses a bug in the log batching processor so that logs are exported immediately when the batch size limit is reached, rather than waiting for the scheduled delay. It also adds and improves tests to ensure the correct export behavior for both full and partial batches, and clarifies the logic for queue size limits.

Bug Fixes and Core Logic:

• Fixed the batchLogProcessor so that it exports logs immediately when maxExportBatchSize is reached, instead of waiting for _scheduledDelayMillis. This ensures timely log delivery and corrects previous batching behavior. [1] [2] [3]

Fixes #5706

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Updated and expanded tests in BatchLogRecordProcessor.test.ts to cover immediate export on batch size, timer-based export for partial batches, multiple immediate exports, and correct handling of queue size limits. [1] [2]
• Improved test clarity by removing unnecessary fake timers where not needed, and by verifying the processor's behavior in a variety of batching and flushing scenarios. [1] [2]

Checklist:

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

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.22%. Comparing base (af28dba) to head (82dd756).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...sdk-logs/src/export/BatchLogRecordProcessorBase.ts	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5961      +/-   ##
==========================================
- Coverage   95.23%   95.22%   -0.01%     
==========================================
  Files         311      311              
  Lines        8596     8603       +7     
  Branches     1799     1801       +2     
==========================================
+ Hits         8186     8192       +6     
- Misses        410      411       +1     

Files with missing lines	Coverage Δ
...sdk-logs/src/export/BatchLogRecordProcessorBase.ts	93.06% <90.00%> (-0.55%)	⬇️

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[trentm]

Thanks for taking this on. We definitely should fix the issue.

[trentm]

Marc reminded me that this exporting code originally derives from the batch Span exporter. And there was a PR there doing a similar thing. I haven't looked at it, but this PR might have changes that could be borrowed: #3958

[trentm]

Thanks!

[trentm]

This line shouldn't have been moved. I think this is an accidental mismerge from #5987.
The changelog line for this PR should also be in experimental/CHANGELOG.md rather than this file.

I'll fix in a sec.