[Extensions] Improves performance by replacing cluster state calls for index existence with exists()/aliasExists() API calls

[joshpalis]

Description

Companion SDK PR : opensearch-project/opensearch-sdk-java#802 (SDK PR must be merged first)

Replaces the following cluster state calls to check if an index/alias exists with the SDKIndicesClient exist() and existsAlias() methods :

• state().getRoutingTable().hasIndex(indexName)
• state().metadata().hasIndex(indexName)
• state().metadata().indices().containsKey(indexName)
• state().metadata().hasAlias(alias)

Issues Resolved

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

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.

[dbwiddis]

LGTM with questions.

[dbwiddis]

Do we need any exception handling here, even if it's just catching and rethrowing with some more information? OK if the answer is no, just wondering what the user experience will be.

(Repeat comment for most of these calls.)

[joshpalis]

I dont think its necessary as the only way this request fails is by timing out, since even if the index/alias does not exist, it would follow the happy path (for lack of a better word). There's no other information to provide.

[joshpalis]

Checks are failing since SDK main has failed to publish to sonatype. See the error here

[owaiskazi19]

Except @dbwiddis comments. Rest LGTM

[codecov]

Codecov Report

Merging #919 (9e7da8f) into feature/extensions (c20e72d) will decrease coverage by 0.39%.
The diff coverage is 10.98%.

@@                   Coverage Diff                    @@
##             feature/extensions     #919      +/-   ##
========================================================
- Coverage                 43.32%   42.94%   -0.39%     
+ Complexity                 2433     2420      -13     
========================================================
  Files                       301      301              
  Lines                     18065    18139      +74     
  Branches                   1872     1872              
========================================================
- Hits                       7826     7789      -37     
- Misses                     9656     9772     +116     
+ Partials                    583      578       -5     

Flag	Coverage Δ
plugin	42.94% <10.98%> (-0.39%)	⬇️

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

Impacted Files	Coverage Δ
.../ad/rest/handler/AnomalyDetectorActionHandler.java	5.12% <0.00%> (-1.54%)	⬇️
...ransport/DeleteAnomalyDetectorTransportAction.java	0.00% <0.00%> (ø)
...transport/StatsAnomalyDetectorTransportAction.java	0.00% <0.00%> (ø)
...c/main/java/org/opensearch/ad/util/IndexUtils.java	1.49% <0.00%> (-0.64%)	⬇️
...c/main/java/org/opensearch/ad/util/ParseUtils.java	53.47% <20.00%> (-6.03%)	⬇️
...opensearch/ad/indices/AnomalyDetectionIndices.java	13.16% <28.57%> (+0.91%)	⬆️

... and 5 files with indirect coverage changes