[Backport 2.x][Remote Publication] Add remote download stats (#15291)

[Arpit-Bandejiya]

Backport #15291 into 2.x branch.

---

Signed-off-by: Arpit Bandejiya [email protected]

(cherry picked from commit b54e867)

Description

[Describe what this change achieves]

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

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

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[github-actions]

✅ Gradle check result for 38d0a82: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 69.76744% with 39 lines in your changes missing coverage. Please review.

Project coverage is 71.76%. Comparing base (8a9c167) to head (6a9198a).
Report is 1 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...ster/coordination/PublicationTransportHandler.java	55.10%	19 Missing and 3 partials ⚠️
...nsearch/gateway/remote/RemotePersistenceStats.java	77.41%	7 Missing ⚠️
...arch/gateway/remote/RemoteClusterStateService.java	77.77%	6 Missing ⚠️
...g/opensearch/cluster/coordination/Coordinator.java	0.00%	2 Missing and 1 partial ⚠️
.../java/org/opensearch/gateway/GatewayMetaState.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #15570      +/-   ##
============================================
+ Coverage     71.64%   71.76%   +0.12%     
- Complexity    63909    63993      +84     
============================================
  Files          5240     5241       +1     
  Lines        299047   299111      +64     
  Branches      43535    43539       +4     
============================================
+ Hits         214244   214653     +409     
+ Misses        66881    66483     -398     
- Partials      17922    17975      +53     

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[Bukhtawar]

Need to fix ChangeLog

[github-actions]

❌ Gradle check result for 2630508: 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 da098ed: 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 6a9198a: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.cluster.MinimumClusterManagerNodesIT.testThreeNodesNoClusterManagerBlock

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