[Bugfix] Fix cache maximum size settings not working properly with pluggable caching

[peteralfonsi]

Description

Fixes a bug (#16631) where max size settings for cache implementations were not working correctly when pluggable caching is on.

The cache implementations like OpenSearchOnHeapCache had been changed so that the max size value from the config overrode the value from their setting. This allowed the TieredSpilloverCache to send different sizes into the cache config when constructing its segments. However, the IndicesRequestCache was also putting its default 1% of heap size value into the cache config, and this overrode the setting values even when pluggable caching was on.

Fixes this by having the IRC only put a max size value into the config if pluggable caching is off.

Adds UTs around this. Also tested manually with different combinations of settings.

Related Issues

Resolves #16631

Check List

• Functionality includes testing.
• [N/A] API changes companion pull request created, if applicable.
• [N/A] Public documentation issue/PR created, if applicable.

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[github-actions]

✅ Gradle check result for 3d1fe73: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 87.09677% with 4 lines in your changes missing coverage. Please review.

Project coverage is 72.08%. Comparing base (10873f1) to head (3d1fe73).
Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
...va/org/opensearch/indices/IndicesRequestCache.java	86.95%	3 Missing ⚠️
.../opensearch/common/cache/service/CacheService.java	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #16636      +/-   ##
============================================
- Coverage     72.15%   72.08%   -0.08%     
- Complexity    65145    65162      +17     
============================================
  Files          5315     5318       +3     
  Lines        303573   303833     +260     
  Branches      43925    43962      +37     
============================================
- Hits         219039   219003      -36     
- Misses        66587    66925     +338     
+ Partials      17947    17905      -42     

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[github-actions]

❌ Gradle check result for 469006a: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❌ Gradle check result for 76ad2ef: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[peteralfonsi]

Flaky tests: #14568, #16015