[TEST] Add test about batch processor with current_thread async runtime

[ThomsonTan]

Changes

Add test to reproduce the deadlock during shutdown of batch processor when configured with single thread async runtime. Related to issue #2066.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[ThomsonTan]

Reproduced the hang in below iteration, ignore running the test in the latest iteration.

https://github.com/open-telemetry/opentelemetry-rust/actions/runs/10907111063/job/30269977617?pr=2123

[codecov]

Codecov Report

Attention: Patch coverage is 70.58824% with 15 lines in your changes missing coverage. Please review.

Project coverage is 78.9%. Comparing base (c93cf26) to head (7c7965c).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
opentelemetry-sdk/src/logs/log_processor.rs	70.5%	15 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2123     +/-   ##
=======================================
- Coverage   78.9%   78.9%   -0.1%     
=======================================
  Files        121     121             
  Lines      20780   20831     +51     
=======================================
+ Hits       16416   16453     +37     
- Misses      4364    4378     +14     

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