[Backport 2.1] Updating multi-field mapping at follower (#671)

[opensearch-trigger-bot]

Backport 475d8da from #680

[codecov-commenter]

Codecov Report

Merging #682 (98f3ebf) into 2.1 (0bc11f0) will increase coverage by 0.33%.
The diff coverage is 85.71%.

@@             Coverage Diff              @@
##                2.1     #682      +/-   ##
============================================
+ Coverage     74.30%   74.63%   +0.33%     
- Complexity      995     1008      +13     
============================================
  Files           141      141              
  Lines          4584     4605      +21     
  Branches        505      510       +5     
============================================
+ Hits           3406     3437      +31     
+ Misses          856      848       -8     
+ Partials        322      320       -2     

Impacted Files	Coverage Δ
...rch/replication/task/index/IndexReplicationTask.kt	72.42% <85.71%> (+0.86%)	⬆️
...cation/action/changes/TransportGetChangesAction.kt	63.49% <0.00%> (-25.40%)	⬇️
...rch/replication/action/status/ShardInfoResponse.kt	91.59% <0.00%> (+19.32%)	⬆️
...arch/replication/metadata/UpdateMetadataRequest.kt	100.00% <0.00%> (+22.72%)	⬆️

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