Refactor stats collector

[sruti1312]

Signed-off-by: Sruti Parthiban [email protected]

Is your feature request related to a problem? Please provide an existing Issue # , or describe.
StatsCollector is used by RCA-Agent and PerformanceAnalyzer Plugin to publish service metrics. We run this collector through ScheduledMetricCollectorsExecutor and the executor can mark the collector as SLOW and subsequently MUTED if the collector is slow. A muted collector doesn't emit any metrics and thus we can end up missing the helpful service metrics.

This PR contains changes to skip muting for StatsCollector and re-factoring to move away from StatExceptionCode to Metric Aggregators.

This is an extension of this PR opensearch-project/performance-analyzer-rca#37.

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Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
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[codecov-commenter]

Codecov Report

Merging #46 (3ed6e63) into main (05314d2) will increase coverage by 0.08%.
The diff coverage is 25.00%.

@@             Coverage Diff              @@
##               main      #46      +/-   ##
============================================
+ Coverage     72.09%   72.18%   +0.08%     
- Complexity      355      356       +1     
============================================
  Files            44       44              
  Lines          2505     2509       +4     
  Branches        160      160              
============================================
+ Hits           1806     1811       +5     
+ Misses          593      592       -1     
  Partials        106      106              

Impacted Files	Coverage Δ
...analyzer/collectors/MasterServiceEventMetrics.java	72.29% <0.00%> (-1.00%)	⬇️
...collectors/NodeStatsAllShardsMetricsCollector.java	87.65% <0.00%> (-0.55%)	⬇️
...nalyzer/config/setting/ClusterSettingsManager.java	5.88% <ø> (ø)
...er/listener/PerformanceAnalyzerSearchListener.java	81.34% <0.00%> (ø)
...llectors/NodeStatsFixedShardsMetricsCollector.java	91.00% <100.00%> (+0.04%)	⬆️
...analyzer/config/PerformanceAnalyzerController.java	79.20% <100.00%> (ø)
...rt/PerformanceAnalyzerTransportRequestHandler.java	78.04% <100.00%> (ø)
...nalyzer/collectors/ThreadPoolMetricsCollector.java	90.66% <0.00%> (ø)
...ormanceanalyzer/writer/EventLogQueueProcessor.java	61.44% <0.00%> (+4.81%)	⬆️

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