Temp refactor cluster metrics monitor suspendUntil() to get().

[AWSHurneyt]

Issue #, if available:

Description of changes:

1. Temp refactor cluster metrics monitor suspendUntil() to get().
2. PR Implemented support for configuring a cluster metrics monitor to call cat/indices, and cat/shards. #992 had some ktlint errors that were not surfaced locally. Fixed those ktlint errors on main branch.

This PR does not need to be backported as the changes were included in the manual backports to the 2.x and 2.9 branches.

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[codecov]

Codecov Report

Merging #1015 (3eb7a41) into main (3911ca9) will decrease coverage by 1.62%.
The diff coverage is 56.49%.

@@             Coverage Diff              @@
##               main    #1015      +/-   ##
============================================
- Coverage     73.83%   72.21%   -1.62%     
  Complexity      113      113              
============================================
  Files           158      160       +2     
  Lines          9326    10294     +968     
  Branches       1365     1570     +205     
============================================
+ Hits           6886     7434     +548     
- Misses         1743     1961     +218     
- Partials        697      899     +202     

Impacted Files	Coverage Δ
...ain/kotlin/org/opensearch/alerting/InputService.kt	89.88% <ø> (ø)
.../clusterMetricsMonitorHelpers/CatIndicesHelpers.kt	55.23% <55.23%> (ø)
...l/clusterMetricsMonitorHelpers/CatShardsHelpers.kt	57.00% <57.00%> (ø)
...lpers/SupportedClusterMetricsSettingsExtensions.kt	54.16% <71.87%> (ø)
...erting/settings/SupportedClusterMetricsSettings.kt	20.00% <100.00%> (+3.72%)	⬆️
.../kotlin/org/opensearch/alerting/util/IndexUtils.kt	78.33% <100.00%> (+0.36%)	⬆️

... and 5 files with indirect coverage changes

[AWSHurneyt]

For reference, the multi node tests started failing in PR #976 (comment). Continuing to investigate.