[Extensions] Improves performance by replacing cluster state calls to retrieve index mappings, cluster index health

[joshpalis]

Description

Companion SDK PR : opensearch-project/opensearch-sdk-java#810 (SDK PR must be merged first )

Replaces the following cluster state calls to retrieve index metadata mapping and to determine cluster index health with GetMappings / ClusterHealth requests using the SDKIndicesClient/SDKClusterAdminClient :

• state().metadata().index(resultIndex)
• state().metadata().index(indexOrAliasName)
• state().getRoutingTable().index(indexOrAliasName)

Issues Resolved

Part of opensearch-project/opensearch-sdk-java#674

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[codecov]

Codecov Report

Merging #921 (c091935) into feature/extensions (56b038f) will decrease coverage by 0.09%.
The diff coverage is 10.52%.

@@                   Coverage Diff                    @@
##             feature/extensions     #921      +/-   ##
========================================================
- Coverage                 42.95%   42.86%   -0.09%     
+ Complexity                 2421     2420       -1     
========================================================
  Files                       301      301              
  Lines                     18139    18169      +30     
  Branches                   1872     1873       +1     
========================================================
- Hits                       7791     7788       -3     
- Misses                     9771     9806      +35     
+ Partials                    577      575       -2     

Flag	Coverage Δ
plugin	42.86% <10.52%> (-0.09%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
.../main/java/org/opensearch/ad/NodeStateManager.java	56.12% <ø> (ø)
...rch/ad/transport/AnomalyResultTransportAction.java	0.00% <ø> (ø)
...c/main/java/org/opensearch/ad/util/IndexUtils.java	1.33% <0.00%> (-0.16%)	⬇️
...opensearch/ad/indices/AnomalyDetectionIndices.java	12.27% <14.81%> (-0.90%)	⬇️

... and 2 files with indirect coverage changes