[Geneva] Do not cache long logger names

[martincostello]

Changes

Apply an upper limit to the length of cached sanitized logger names added in #4498.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[Copilot]

Pull request overview

This PR tightens the Geneva exporter’s sanitized logger category-name cache by introducing a maximum input length for cache entries, preventing excessively long logger names from being retained in the memoization dictionary (while still returning a correctly sanitized/truncated event name).

Changes:

• Add MaxCachedCategoryNameLength (512) and skip cache insertion for category names longer than this limit.
• Add unit tests covering the “at limit cached” vs “over limit not cached” behavior for sanitized category names.
• Update the Geneva exporter changelog entry to reference this follow-up PR alongside the original optimization PR (#4498).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
test/OpenTelemetry.Exporter.Geneva.Tests/TldLogCommonSanitizationTests.cs	Adds tests validating caching behavior at and above the maximum cached category-name length.
src/OpenTelemetry.Exporter.Geneva/Internal/Tld/TldLogCommon.cs	Introduces a max length guard to avoid caching pathologically long logger category names.
src/OpenTelemetry.Exporter.Geneva/CHANGELOG.md	Updates the existing allocations-reduction changelog entry to include this PR reference.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.33%. Comparing base (10c296b) to head (e43cc67).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4684   +/-   ##
=======================================
  Coverage   77.33%   77.33%           
=======================================
  Files         466      466           
  Lines       19705    19707    +2     
=======================================
+ Hits        15239    15241    +2     
  Misses       4466     4466           

Flag	Coverage Δ
unittests-Exporter.Geneva	56.76% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...metry.Exporter.Geneva/Internal/Tld/TldLogCommon.cs	66.91% <100.00%> (+0.50%)	⬆️

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[Kielek]

@petrroll FYI

[Kielek]

LGTM