feat(simple reader): Destroy MRDinstance & remove it from cache when inode is destroyed

[abhishek10004]

Description

1. Destroy MRDinstance & remove it from cache when inode is destroyed.
2. Handled an edge case, when MRDInstance was re-added to the cache before eviction, in DecrementRefCount flow.
3. Refactored the code.
4. Added UTs

Link to the issue in case of a bug fix.

b/474070647

Testing details

1. Manual - NA
2. Unit tests - Done
3. Integration tests - NA

Any backward incompatible change? If so, please explain.

[abhishek10004]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces important improvements to the lifecycle management of MrdInstance. By ensuring that the MrdInstance is destroyed and removed from the cache when its owning inode is destroyed, it effectively prevents potential resource leaks. The refactoring of the cache eviction logic into the MrdInstance itself is a great change that improves encapsulation and clarity. I was particularly impressed with the handling of the race condition where an instance could be re-added to the cache before its eviction is processed. The new unit tests are comprehensive and thoroughly cover the new logic and edge cases. The changes are well-implemented and significantly enhance the robustness of the code. Great work!

[codecov]

Codecov Report

❌ Patch coverage is 89.65517% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.10%. Comparing base (fe4a578) to head (6cd4d67).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/gcsx/mrd_instance.go	87.50%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4262      +/-   ##
==========================================
+ Coverage   83.06%   83.10%   +0.03%     
==========================================
  Files         159      159              
  Lines       19235    19249      +14     
==========================================
+ Hits        15977    15996      +19     
+ Misses       2666     2663       -3     
+ Partials      592      590       -2     

Flag	Coverage Δ
unittests	83.10% <89.65%> (+0.03%)	⬆️

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[github-actions]

Hi @raj-prince, @vadlakondaswetha, your feedback is needed to move this pull request forward. This automated reminder was triggered because there has been no activity for over 24 hours. Please provide your input when you have a moment. Thank you!

[github-actions]

Hi @raj-prince, @vadlakondaswetha, your feedback is needed to move this pull request forward. This automated reminder was triggered because there has been no activity for over 24 hours. Please provide your input when you have a moment. Thank you!

[raj-prince]

LGTM.