[2.x] Deprecated reserved node id '_must_join_elected_master_' that used by DetachClusterCommand and replace with '_must_join_elected_cluster_manager_'

[tlfeng]

Description

Backport PR #3116 to 2.x branch.

To support inclusive language, replace "master" with "cluster manager".

• Deprecate public field MUST_JOIN_ELECTED_MASTER and replace with MUST_JOIN_ELECTED_CLUSTER_MANAGER in VotingConfiguration class
• Rename the preserved node id _must_join_elected_master_ to _must_join_elected_cluster_manager_
• VotingConfiguration.MUST_JOIN_ELECTED_MASTER is only read by ClusterFormationFailureHelper, and make it accept both MUST_JOIN_ELECTED_MASTER and MUST_JOIN_ELECTED_CLUSTER_MANAGER
• Add unit test

The original _must_join_elected_master_ is only used as a preserved node id for "Detach Cluster Command" (https://github.com/opensearch-project/OpenSearch/blob/1.3.1/server/src/main/java/org/opensearch/cluster/coordination/DetachClusterCommand.java#L89).
"Detach Cluster Command" ./bin/opensearch-node detach-cluster can detach a node from its cluster by resetting its cluster UUID. The node can then join another cluster with a different UUID. _must_join_elected_master_ is set as a node id and used as an identifier for the node processed by "Detach Cluster Command".

Issues Resolved

A part of #1548

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

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.

[opensearch-ci-bot]

✅   Gradle Check success 65bdfc4be09fa3c0228abc4990b4199b4ae11c66
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Reports 4922

[opensearch-ci-bot]

✅   Gradle Check success c24d428
Log 4923

Reports 4923

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.x 2.x
# Navigate to the new working tree
cd .worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-3138-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 97a6f2c2f58d6270c94e376b4716445cf98619e2
# Push it to GitHub
git push --set-upstream origin backport/backport-3138-to-2.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-3138-to-2.x.

[tlfeng]

@dblock Thanks a lot for your time in reviewing my PR! 🏅