Rename cluster settings following new 2.x convention

[peternied]

Description

Previously the setting was cluster.initial_master_nodes and has since
changed to cluster.initial_cluster_manager_nodes. This was causing
issues due to a bug in the fallback method that has been fixed in
OpenSearch, but getting ahead of this change before its needed.

Issues

See related opensearch-project/OpenSearch#2779

Check List

• New functionality includes testing
• New functionality has been documented
• 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.

[cliu123]

The related issue blocking 2.0.0 has been fixed in OpenSearch core. This change can be a part of other inclusive renaming changes later in future release.

[codecov-commenter]

Codecov Report

Merging #1746 (127a7fa) into main (54a920b) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #1746      +/-   ##
============================================
- Coverage     60.42%   60.42%   -0.01%     
  Complexity     3197     3197              
============================================
  Files           253      253              
  Lines         18093    18092       -1     
  Branches       3245     3245              
============================================
- Hits          10933    10932       -1     
  Misses         5579     5579              
  Partials       1581     1581              

Impacted Files	Coverage Δ
...ecurity/ssl/rest/SecuritySSLReloadCertsAction.java	84.78% <0.00%> (-0.33%)	⬇️

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[davidlago]

Following this comment we might wan to reassess merging this PR for 2.0

[peternied]

@davidlago Was this still up for consideration in the 2.0.0 release? As we are past the code freeze deadline it seems like this should be merged into the 2.X branch for the next release train.

[peternied]

There is an issue in security plugin opensearch-project/security#1746 that we are considering to merge post code freeze. There has been a setting that was renamed as part of inclusive naming in opensearch core which is used in security plugin scripts.
Pros: New inclusive terms usage is in alignment within our release, its a focused change that is validated by CI checks before entering the distribution build. There is a minimal risk of destabilizing perf/stress tests in progress
Cons: Additional inclusive terminology changes are not in for security plugin, and has no outward facing impact making it a good candidate for the next patch release.

[Recapping offline conversation] While this change would be valuable, it does not meet the requirements for the 2.0.0-rc1 release. There are concerns about modifying the setup scripts late in the process. We will add this to the next release.

From opensearch-project/opensearch-build#1624 (comment)

[peternied]

@opensearch-project/security Since we've diverged into a 2.0 branch, lets see about merging this pull request