Add unreferenced file cleanup count to merge stats

[RS146BIJAY]

Description

Adding stats for unreferenced files cleanup count on segment merge failure due to disk full.

unreferenced_file_cleanup.count: Number of times unreferenced files are cleaned up on segment merge failures.

"indices": {
        "merges": {
          "current": 0,
          "current_docs": 0,
          "current_size_in_bytes": 0,
          "total": 0,
          "total_time_in_millis": 0,
          "total_docs": 0,
          "total_size_in_bytes": 0,
          "total_stopped_time_in_millis": 0,
          "total_throttled_time_in_millis": 0,
          "total_auto_throttle_in_bytes": 120109614,
          "unreferenced_file_cleanup_count": 3
        }
      }

Related Issues

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

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

Compatibility status:

Checks if related components are compatible with change 6817c01

Incompatible components

Skipped components

Compatible components

Compatible components: [https://github.com/opensearch-project/security.git, https://github.com/opensearch-project/alerting.git, https://github.com/opensearch-project/index-management.git, https://github.com/opensearch-project/anomaly-detection.git, https://github.com/opensearch-project/sql.git, https://github.com/opensearch-project/job-scheduler.git, https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/k-nn.git, https://github.com/opensearch-project/reporting.git, https://github.com/opensearch-project/cross-cluster-replication.git, https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/custom-codecs.git, https://github.com/opensearch-project/ml-commons.git, https://github.com/opensearch-project/performance-analyzer.git, https://github.com/opensearch-project/opensearch-oci-object-storage.git, https://github.com/opensearch-project/performance-analyzer-rca.git, https://github.com/opensearch-project/geospatial.git, https://github.com/opensearch-project/notifications.git, https://github.com/opensearch-project/neural-search.git]

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26204/
• CommitID: 67212b2
  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 (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/26205/
• CommitID: 5d2f215

[codecov]

Codecov Report

Merging #10204 (6817c01) into main (d3bf230) will increase coverage by 0.03%.
Report is 4 commits behind head on main.
The diff coverage is 73.33%.

@@             Coverage Diff              @@
##               main   #10204      +/-   ##
============================================
+ Coverage     71.15%   71.18%   +0.03%     
- Complexity    58247    58306      +59     
============================================
  Files          4831     4831              
  Lines        274684   274704      +20     
  Branches      40026    40030       +4     
============================================
+ Hits         195443   195555     +112     
+ Misses        62884    62785      -99     
- Partials      16357    16364       +7     

Files	Coverage Δ
...rch/extensions/rest/RestActionsRequestHandler.java	100.00% <100.00%> (ø)
...extensions/rest/RestInitializeExtensionAction.java	65.00% <100.00%> (-0.44%)	⬇️
...rch/extensions/rest/RestSendToExtensionAction.java	42.14% <100.00%> (ø)
.../main/java/org/opensearch/index/engine/Engine.java	74.65% <100.00%> (-1.59%)	⬇️
...in/java/org/opensearch/index/shard/IndexShard.java	70.17% <100.00%> (+0.13%)	⬆️
...va/org/opensearch/search/DefaultSearchContext.java	77.41% <0.00%> (-0.56%)	⬇️
...a/org/opensearch/extensions/ExtensionsManager.java	52.14% <62.50%> (+8.12%)	⬆️
...in/java/org/opensearch/index/merge/MergeStats.java	78.35% <70.00%> (-1.43%)	⬇️

... and 450 files with indirect coverage changes

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26539/
• CommitID: 8781702
  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 (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.snapshots.CloneSnapshotIT.testCloneShallowSnapshotIndex

• URL: https://build.ci.opensearch.org/job/gradle-check/26541/
• CommitID: 4fc4bbc
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26668/
• CommitID: 0b1ade2
  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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26670/
• CommitID: 118af10
  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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26671/
• CommitID: 1cf7b41
  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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26674/
• CommitID: dc9785d
  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 (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/26673/
• CommitID: 56d5eb1

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26675/
• CommitID: 6817c01
  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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26682/
• CommitID: 6817c01
  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 (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/26686/
• CommitID: 6817c01