Introduce a new feature flag "WRITEABLE_REMOTE_INDEX" to gate the writeable remote index functionality

[Rishikesh1159]

Description

This PR introduces new WRITEABLE_REMOTE_INDEX feature flag to gate the writeable remote index functionality.

Related Issues

Resolves #11705

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• Public documentation issue/PR created

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[github-actions]

Compatibility status:

Checks if related components are compatible with change 5fa405b

Incompatible components

Skipped components

Compatible components

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

[github-actions]

❕ Gradle check result for 007a3cd: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.remotestore.RemoteIndexPrimaryRelocationIT.testPrimaryRelocationWhileIndexing

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

All modified and coverable lines are covered by tests ✅

Comparison is base (7b1c2c7) 71.41% compared to head (5fa405b) 71.32%.
Report is 11 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #11717      +/-   ##
============================================
- Coverage     71.41%   71.32%   -0.09%     
+ Complexity    59232    59208      -24     
============================================
  Files          4909     4909              
  Lines        278427   278428       +1     
  Branches      40460    40460              
============================================
- Hits         198826   198588     -238     
- Misses        63141    63386     +245     
+ Partials      16460    16454       -6     

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[kotwanikunal]

Can you also add in a CHANGELOG entry?

[github-actions]

❌ Gradle check result for 32c3d01: 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 32c3d01: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.remotestore.RemoteIndexPrimaryRelocationIT.testPrimaryRelocationWhileIndexing

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 result for 5fa405b: 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?

[Rishikesh1159]

❌ Gradle check result for 5fa405b: 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?

known flaky test: #10006

[github-actions]

❕ Gradle check result for 5fa405b: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.remotestore.RemoteIndexPrimaryRelocationIT.testPrimaryRelocationWhileIndexing

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