[Backport 3.2] Expose SETTING_GRPC_MAX_MSG_SIZE to settings service

[opensearch-trigger-bot]

Backport bf5b43d from #18910.

[finnegancarroll]

@prudhvigodithi can merge this bugfix when CI passes?

[prudhvigodithi]

@finnegancarroll we should update the 3.2 release notes as well, can you please check?

[github-actions]

✅ Gradle check result for 2eec24a: SUCCESS

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (3.2@5ce98e5). Learn more about missing BASE report.

Additional details and impacted files

@@          Coverage Diff           @@
##             3.2   #18954   +/-   ##
======================================
  Coverage       ?   72.87%           
  Complexity     ?    69307           
======================================
  Files          ?     5642           
  Lines          ?   318636           
  Branches       ?    46107           
======================================
  Hits           ?   232199           
  Misses         ?    67602           
  Partials       ?    18835           

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[prudhvigodithi]

@finnegancarroll we should update the 3.2 release notes as well, can you please check?

NVM I see skip changelog label added to the original PR #18910. So we should be good.