Updating the separator for RemoteStoreLockManager since underscore is allowed in base64UUID url charset

[harishbhakuni]

Description

We are using URL Safe Base64UUID in most of the places in code which can have '__' as one of the characters. For Remote Store Metadata Lock files, Keeping '___' (triple underscores) as separator to separate out snapshot UUID and remote store metadata name would not work because if either the Metadata or the Snapshot UUID starts or ends will '', we cannot use our separator to separate out the fields.

To Fix this, as part of this PR I am updating the separator to "..." for new lock files. We will still support reading older lock files for backward compatibility, but we will do best effort by pulling out the snapshotID from the end first and then getting the md file.

Related Issues

Resolves #9115

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)
• GitHub issue/PR created in OpenSearch documentation repo for the required public documentation changes (#[Issue/PR number])

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[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/27026/
• CommitID: 56ff047
  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]

Compatibility status:

Checks if related components are compatible with change b8adac0

Incompatible components

Skipped components

Compatible components

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

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/27161/
• CommitID: bda47d6
  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.index.reindex.UpdateByQueryBasicTests.classMethod

• URL: https://build.ci.opensearch.org/job/gradle-check/27163/
• CommitID: ef55857
  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/27175/
• CommitID: 8471688
  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/27177/
• CommitID: b8adac0

[sohami]

Merging as gradle check passed and pre-commit was successful locally as well.