[Backport 2.x] Add update settings allowlist for searchable snapshot

[opensearch-trigger-bot]

Backport 011ff63 from #5907.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.cluster.allocation.AwarenessAllocationIT.testThreeZoneOneReplicaWithForceZoneValueAndLoadAwareness

• URL: https://build.ci.opensearch.org/job/gradle-check/9711/
• CommitID: 28ca159
  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-commenter]

Codecov Report

Merging #5967 (28ca159) into 2.x (23c23dc) will increase coverage by 0.03%.
The diff coverage is 51.74%.

@@             Coverage Diff              @@
##                2.x    #5967      +/-   ##
============================================
+ Coverage     70.40%   70.43%   +0.03%     
- Complexity    58879    58928      +49     
============================================
  Files          4766     4768       +2     
  Lines        282430   282572     +142     
  Branches      41129    41148      +19     
============================================
+ Hits         198840   199032     +192     
+ Misses        66925    66890      -35     
+ Partials      16665    16650      -15     

Impacted Files	Coverage Δ
...ensearch/analysis/common/CommonAnalysisPlugin.java	92.06% <ø> (ø)
...nsearch/ingest/geoip/DatabaseReaderLazyLoader.java	75.00% <ø> (ø)
...n/java/org/opensearch/painless/PainlessPlugin.java	80.95% <ø> (ø)
...g/opensearch/percolator/PercolateQueryBuilder.java	83.00% <ø> (ø)
...ain/java/org/opensearch/systemd/SystemdPlugin.java	74.41% <ø> (ø)
...in/java/org/opensearch/transport/Netty4Plugin.java	73.68% <ø> (ø)
...earch/plugin/discovery/gce/GceDiscoveryPlugin.java	20.83% <ø> (ø)
...rg/opensearch/repositories/s3/S3BlobContainer.java	37.97% <ø> (-1.69%)	⬇️
...g/opensearch/transport/nio/NioTransportPlugin.java	25.00% <ø> (ø)
...earch/action/search/AbstractSearchAsyncAction.java	77.38% <ø> (-0.30%)	⬇️
... and 535 more

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