feat(sdk-logs)!: configure force flush timeout per call

[LarryHu0217]

Which problem is this PR solving?

LoggerProviderOptions.forceFlushTimeoutMillis cannot be supplied through declarative configuration because it controls a later forceFlush() call rather than provider construction.

Fixes #6927

Short description of the changes

• remove forceFlushTimeoutMillis from LoggerProviderOptions
• add an exported ForceFlushOptions object with timeoutMillis
• pass the per-call timeout through LoggerProvider to MultiLogRecordProcessor
• preserve the existing 30-second default when no timeout is supplied
• update unit-test fixtures and the experimental changelog

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?

• npx --no-install nx run @opentelemetry/sdk-logs:compile --skip-nx-cache
• npx --no-install nx run @opentelemetry/sdk-logs:test --skip-nx-cache (202 passing, 9 pending browser-only tests)
• npx --no-install nx run @opentelemetry/sdk-logs:lint --skip-nx-cache
• Prettier check for all touched TypeScript files
• Markdown lint for experimental/CHANGELOG.md

Checklist:

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.07%. Comparing base (4e8c9fd) to head (1360413).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6931      +/-   ##
==========================================
- Coverage   95.07%   95.07%   -0.01%     
==========================================
  Files         409      409              
  Lines       14243    14240       -3     
  Branches     3267     3267              
==========================================
- Hits        13542    13539       -3     
  Misses        701      701              

Files with missing lines	Coverage Δ
...perimental/packages/sdk-logs/src/LoggerProvider.ts	100.00% <100.00%> (ø)
...l/packages/sdk-logs/src/MultiLogRecordProcessor.ts	100.00% <100.00%> (ø)
...sdk-logs/src/internal/LoggerProviderSharedState.ts	97.29% <ø> (-0.08%)	⬇️

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[opentelemetry-pr-dashboard]

Pull request dashboard status

• Status: Merged.

[otelbot]

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