Fix custom metadata not getting stored for remote store not supporting async write

[dhwanilpatel]

Description

Fix custom metadata not getting stored for remote store not supporting async write.

Related Issues

#10691
#10697

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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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 f41dc14

Incompatible components

Incompatible components: [https://github.com/opensearch-project/cross-cluster-replication.git]

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/job-scheduler.git, https://github.com/opensearch-project/sql.git, https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/k-nn.git, https://github.com/opensearch-project/reporting.git, https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/custom-codecs.git, https://github.com/opensearch-project/opensearch-oci-object-storage.git, https://github.com/opensearch-project/performance-analyzer.git, https://github.com/opensearch-project/ml-commons.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: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/28676/
• CommitID: f41dc14

[codecov]

Codecov Report

Merging #10812 (f41dc14) into main (51626d0) will increase coverage by 0.00%.
Report is 1 commits behind head on main.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##               main   #10812   +/-   ##
=========================================
  Coverage     71.31%   71.31%           
- Complexity    58671    58673    +2     
=========================================
  Files          4860     4860           
  Lines        276335   276338    +3     
  Branches      40198    40198           
=========================================
+ Hits         197068   197073    +5     
- Misses        62803    62843   +40     
+ Partials      16464    16422   -42     

Files	Coverage Δ
...arch/gateway/remote/RemoteClusterStateService.java	69.80% <100.00%> (+0.06%)	⬆️
...epositories/blobstore/ChecksumBlobStoreFormat.java	95.16% <100.00%> (+0.16%)	⬆️

... and 449 files with indirect coverage changes

[linuxpi]

LGTM