test(native): add coverage for max cache items/size/age

[jpnurmi]

• Parameterizes test_integration_cache.py for the native backend to add missing native coverage for cache max size, max age, max items, and retry item limits.
• Moves the remaining cache tests from test_integration_native.py to test_integration_cache.py.
• Promotes the run_crash helper for reuse outside test_integration_native.py.

[cursor]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.79%. Comparing base (17b3f62) to head (4ca4bae).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1892      +/-   ##
==========================================
+ Coverage   75.77%   75.79%   +0.01%     
==========================================
  Files          92       92              
  Lines       21985    21985              
  Branches     3917     3917              
==========================================
+ Hits        16659    16663       +4     
+ Misses       4444     4441       -3     
+ Partials      882      881       -1     

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