[Extensions] Fixed duplicate extension unique id

[owaiskazi19]

Description

The header extension_unique_id is being set twice, in OpenSearch and here in SDK for the case when extension is getting initialized. This header helps OpenSearch to recognize node as an extension node while doing connectToExtensionNode. The issue was mostly with threadContext restoring the header and trying to set it again.

Related Issues

Closes opensearch-project/opensearch-sdk-java#771

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]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.repositories.azure.AzureBlobContainerRetriesTests.testReadNonexistentBlobThrowsNoSuchFileException
      1 org.opensearch.remotestore.RemoteStoreRefreshListenerIT.testRemoteRefreshRetryOnFailure

• URL: https://build.ci.opensearch.org/job/gradle-check/18205/
• CommitID: 4cc6ede
  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

Merging #8228 (f15e242) into main (84dffac) will increase coverage by 0.08%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##               main    #8228      +/-   ##
============================================
+ Coverage     70.83%   70.92%   +0.08%     
- Complexity    56652    56715      +63     
============================================
  Files          4733     4733              
  Lines        268125   268127       +2     
  Branches      39283    39284       +1     
============================================
+ Hits         189932   190166     +234     
+ Misses        62154    61914     -240     
- Partials      16039    16047       +8     

Impacted Files	Coverage Δ
...ava/org/opensearch/transport/TransportService.java	79.42% <0.00%> (-0.29%)	⬇️

... and 472 files with indirect coverage changes

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testCancelPrimaryAllocation

• URL: https://build.ci.opensearch.org/job/gradle-check/18206/
• CommitID: ac39864
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[dbwiddis]

Approved as a workaround but I think this can be improved.

[dbwiddis]

LGTM!

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testPrimaryStopped_ReplicaPromoted

• URL: https://build.ci.opensearch.org/job/gradle-check/18258/
• CommitID: d2e28f0
  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: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.snapshots.DedicatedClusterSnapshotRestoreIT.testIndexDeletionDuringSnapshotCreationInQueue
      1 org.opensearch.remotestore.RemoteStoreRefreshListenerIT.testRemoteRefreshRetryOnFailure

• URL: https://build.ci.opensearch.org/job/gradle-check/18260/
• CommitID: c031968
  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/18262/
• CommitID: 1ebc1d3
  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.DedicatedClusterSnapshotRestoreIT.testIndexDeletionDuringSnapshotCreationInQueue
      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testDropPrimaryDuringReplication
      1 org.opensearch.gateway.RecoveryFromGatewayIT.testReuseInFileBasedPeerRecovery
      1 org.opensearch.action.admin.cluster.node.tasks.ResourceAwareTasksTests.testBasicTaskResourceTracking

• URL: https://build.ci.opensearch.org/job/gradle-check/18265/
• CommitID: f15e242
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.