Backport removal of runBlocking and Stats API fix

[qreshi]

Issue #, if available:

Description of changes:
Backport #281 and #283 to 1.2

CheckList:
[x] Commits are signed per the DCO using --signoff

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[codecov-commenter]

Codecov Report

Merging #284 (e53953f) into 1.2 (a4597de) will increase coverage by 0.17%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##                1.2     #284      +/-   ##
============================================
+ Coverage     78.45%   78.63%   +0.17%     
- Complexity      211      214       +3     
============================================
  Files           173      173              
  Lines          6959     6964       +5     
  Branches        912      912              
============================================
+ Hits           5460     5476      +16     
+ Misses         1017     1003      -14     
- Partials        482      485       +3     

Impacted Files	Coverage Δ
...in/kotlin/org/opensearch/alerting/MonitorRunner.kt	72.05% <100.00%> (ø)
...ing/core/action/node/ScheduledJobsStatsResponse.kt	65.38% <100.00%> (+1.38%)	⬆️
...pensearch/alerting/elasticapi/ElasticExtensions.kt	55.35% <100.00%> (+3.43%)	⬆️
...ain/kotlin/org/opensearch/alerting/AlertService.kt	78.53% <0.00%> (-0.49%)	⬇️
...e/action/node/ScheduledJobsStatsTransportAction.kt	75.51% <0.00%> (ø)
.../opensearch/alerting/core/schedule/JobScheduler.kt	76.38% <0.00%> (+6.94%)	⬆️
...rch/alerting/core/action/node/ScheduledJobStats.kt	66.66% <0.00%> (+11.11%)	⬆️
...arch/alerting/core/schedule/JobSchedulerMetrics.kt	72.22% <0.00%> (+16.66%)	⬆️

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[qreshi]

Judging from the GitHub Action run results from the original PR of this change on main, the security tests there were never actually run because it deemed that the security plugin couldn't be found (this was for the 1.3.0 Docker image, doesn't seem to be the case for the older versions since it was able to fail here).

Because of this, I ended up using this PR to debug the security tests written for this change since they weren't actually passing. I'm able to get a clean pass now but I'm going to force push this PR to not include the recent changes so I can submit the change as a follow-up PR from main -> 1.x -> etc.