[Backport 2.x] Shallow snapshot v2 - create snapshot validations in a cluster state update

[opensearch-trigger-bot]

Backport e8b02c9 from #15939.

[github-actions]

❌ Gradle check result for e0cc74f: 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 e0cc74f: 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 e0cc74f: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 34.70588% with 111 lines in your changes missing coverage. Please review.

Project coverage is 71.64%. Comparing base (6375b62) to head (e0cc74f).
Report is 10 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...ava/org/opensearch/snapshots/SnapshotsService.java	31.54%	97 Missing and 5 partials ⚠️
...va/org/opensearch/cluster/SnapshotsInProgress.java	57.14%	5 Missing and 4 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #16102      +/-   ##
============================================
- Coverage     71.80%   71.64%   -0.16%     
+ Complexity    64822    64706     -116     
============================================
  Files          5278     5278              
  Lines        302661   302764     +103     
  Branches      44033    44051      +18     
============================================
- Hits         217328   216918     -410     
- Misses        67190    67728     +538     
+ Partials      18143    18118      -25     

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