[Backport 2.x] [SnapshotV2] Add timestamp of last successful fetch of pinned timestamps in node stats

[opensearch-trigger-bot]

Backport be9f942 from #15611.

[github-actions]

❌ Gradle check result for 949714b: 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?

[ltaragi]

❌ Gradle check result for 949714b: 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?

Flaky test #14324

[github-actions]

❕ Gradle check result for 8e07111: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.gateway.RecoveryFromGatewayIT.testShardStoreFetchMultiNodeMultiIndexesUsingBatchAction

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[codecov]

Codecov Report

Attention: Patch coverage is 48.57143% with 18 lines in your changes missing coverage. Please review.

Project coverage is 71.73%. Comparing base (afd1cbc) to head (8e07111).
Report is 1 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...nsearch/node/remotestore/RemoteStoreNodeStats.java	45.00%	8 Missing and 3 partials ⚠️
...rch/action/admin/cluster/node/stats/NodeStats.java	44.44%	3 Missing and 2 partials ⚠️
...src/main/java/org/opensearch/node/NodeService.java	0.00%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #16155      +/-   ##
============================================
- Coverage     71.78%   71.73%   -0.06%     
+ Complexity    64831    64791      -40     
============================================
  Files          5278     5279       +1     
  Lines        302881   302913      +32     
  Branches      44060    44066       +6     
============================================
- Hits         217428   217282     -146     
- Misses        67296    67492     +196     
+ Partials      18157    18139      -18     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.