[Backport 2.x] Implement microbenchmark for FileCache

[opensearch-trigger-bot]

Backport 5eed61e from #6610.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/13063/
• CommitID: eb36f9c
  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?

[codecov-commenter]

Codecov Report

Merging #6886 (d4eede6) into 2.x (d4eede6) will not change coverage.
The diff coverage is n/a.

❗ Current head d4eede6 differs from pull request most recent head eb36f9c. Consider uploading reports for the commit eb36f9c to get more accurate results

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

@@            Coverage Diff            @@
##                2.x    #6886   +/-   ##
=========================================
  Coverage     70.42%   70.42%           
  Complexity    59444    59444           
=========================================
  Files          4810     4810           
  Lines        285519   285519           
  Branches      41510    41510           
=========================================
  Hits         201069   201069           
  Misses        67595    67595           
  Partials      16855    16855           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/13075/
• CommitID: eb36f9c
  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?

[andrross]

Gradle Check (Jenkins) Run Completed with:

* **RESULT:** FAILURE ❌

* **URL:** https://build.ci.opensearch.org/job/gradle-check/13075/

* **CommitID:** [eb36f9c](https://github.com/opensearch-project/OpenSearch/commit/eb36f9c717561f700f66469026274131f9855a0a)
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure [a flaky test](https://github.com/opensearch-project/OpenSearch/blob/main/DEVELOPER_GUIDE.md#flaky-tests) unrelated to your change?

#6287

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.backwards.MixedClusterClientYamlTestSuiteIT.test {p0=pit/10_basic/Delete all}
      1 org.opensearch.backwards.MixedClusterClientYamlTestSuiteIT.test {p0=indices.split/30_copy_settings/Copy settings during split index}
      1 org.opensearch.backwards.MixedClusterClientYamlTestSuiteIT.test {p0=indices.shrink/30_copy_settings/Copy settings during shrink index}

• URL: https://build.ci.opensearch.org/job/gradle-check/13077/
• CommitID: eb36f9c
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.