Infer managedServiceSourceSnapshotEnabled when not set

[AndreKurait]

Description

Infer managedServiceSourceSnapshotEnabled when not set, setting to true if sigv4 auth is set on the source.

• Category: Enhancement
• Why these changes are required? Customer encountered failure when set sigv4 source auth but did not set managedServiceSourceSnapshotEnabled
• What is the old behavior before changes and new behavior after changes? managedServiceSourceSnapshotEnabled was required for managed service auth, now sigv4 can just be set.

Issues Resolved

https://opensearch.atlassian.net/browse/MIGRATIONS-2233

Is this a backport? If so, please add backport PR # and/or commits #

Testing

Added unit testing

Check List

• New functionality includes testing
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented
• Commits are signed per the DCO using --signoff

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.95%. Comparing base (18e83bb) to head (57ec890).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1165   +/-   ##
=========================================
  Coverage     80.94%   80.95%           
- Complexity     2995     2996    +1     
=========================================
  Files           407      407           
  Lines         15229    15229           
  Branches       1023     1023           
=========================================
+ Hits          12327    12328    +1     
+ Misses         2273     2272    -1     
  Partials        629      629           

Flag	Coverage Δ
unittests	80.95% <ø> (+<0.01%)	⬆️

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[lewijacn]

LGTM