[Backport 2.6] Handling OpenSearchRejectExecuteException Exception (#1004)

[sricharanvuppu]

• Handling OpenSearchRejectExecuteException Exception
• introduced writersPerShard setting.

(cherry picked from commit 448e7a7)

Description

[Describe what this change achieves]

Issues Resolved

[List any issues this PR will resolve]

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

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[codecov]

Codecov Report

Merging #1017 (b0aab00) into 2.6 (2b56944) will increase coverage by 2.08%.
Report is 2 commits behind head on 2.6.
The diff coverage is 69.44%.

❗ Current head b0aab00 differs from pull request most recent head d686917. Consider uploading reports for the commit d686917 to get more accurate results

@@             Coverage Diff              @@
##                2.6    #1017      +/-   ##
============================================
+ Coverage     74.18%   76.27%   +2.08%     
- Complexity     1018     1045      +27     
============================================
  Files           141      141              
  Lines          4688     4724      +36     
  Branches        521      527       +6     
============================================
+ Hits           3478     3603     +125     
+ Misses          882      785      -97     
- Partials        328      336       +8     

Files	Coverage Δ
...in/org/opensearch/replication/ReplicationPlugin.kt	90.60% <100.00%> (+0.19%)	⬆️
.../org/opensearch/replication/ReplicationSettings.kt	100.00% <100.00%> (ø)
...on/resume/TransportResumeIndexReplicationAction.kt	86.95% <100.00%> (-0.37%)	⬇️
...ication/seqno/RemoteClusterRetentionLeaseHelper.kt	72.44% <100.00%> (ø)
...rch/replication/task/shard/ShardReplicationTask.kt	75.18% <100.00%> (ø)
...org/opensearch/replication/ReplicationException.kt	11.11% <20.00%> (-3.18%)	⬇️
...tlin/org/opensearch/replication/util/Extensions.kt	68.13% <58.33%> (-2.11%)	⬇️
...search/replication/task/shard/TranslogSequencer.kt	78.46% <68.29%> (-6.91%)	⬇️

... and 12 files with indirect coverage changes