Searchbackpressure Service Reader and UTs added

[CoderJeffrey]

Signed-off-by: Jeffrey Liu ujeffliu@amazon.com

Is your feature request related to a problem? Please provide an existing Issue # , or describe.
To fix on issue #424. The PR mainly adds the reader to consume SearchBackPressure Service metrics.

Describe the solution you are proposing
Adds the reader (processor and snapshot) for SearchBackPressureServiceStats and populate the extracted fields into the sqlitedb. Also add the UTs to test both SearchBackPressureMetricsProcessor.java and SearchBackPressureMetricsSnapShot.java.

Describe alternatives you've considered
N/A

Additional context

1. Parallel PR needs to be approved to pass the Build Test (PR Handling empty flow unit during Cache/Queue RCA execution #34 for the Commons Package) (Constants added for searchbackpressure rca reader to consume searchbackpressure metrics in shared folder performance-analyzer-commons#34). This PR adds the Constants needed by reader to consume metrics in shared folder.

2. This PR is built upon the changes of the other 2 PR for performance-analyzer and performance-analyzer-commons

Check List

• New functionality includes testing.
• All tests pass
• New functionality has been documented.
• New functionality has javadoc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
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[codecov]

Codecov Report

Merging #427 (0bc0d10) into main (efa0fa0) will increase coverage by 0.19%.
The diff coverage is 91.40%.

❗ Current head 0bc0d10 differs from pull request most recent head 16b6db4. Consider uploading reports for the commit 16b6db4 to get more accurate results

@@             Coverage Diff              @@
##               main     #427      +/-   ##
============================================
+ Coverage     75.98%   76.18%   +0.19%     
- Complexity     2581     2601      +20     
============================================
  Files           302      304       +2     
  Lines         15356    15577     +221     
  Branches       1213     1219       +6     
============================================
+ Hits          11669    11867     +198     
- Misses         3193     3211      +18     
- Partials        494      499       +5     

Impacted Files	Coverage Δ
...nceanalyzer/rca/store/OpenSearchAnalysisGraph.java	100.00% <ø> (ø)
...rch/performanceanalyzer/reader/MetricsEmitter.java	94.83% <83.33%> (-0.82%)	⬇️
...zer/reader/SearchBackPressureMetricsProcessor.java	89.18% <89.18%> (ø)
...yzer/reader/SearchBackPressureMetricsSnapShot.java	98.63% <98.63%> (ø)
...eanalyzer/rca/framework/metrics/ReaderMetrics.java	97.56% <100.00%> (+0.06%)	⬆️
...ormanceanalyzer/reader/ReaderMetricsProcessor.java	79.33% <100.00%> (+0.61%)	⬆️

... and 3 files with indirect coverage changes

[khushbr]

LGTM! Thank you for making this change @CoderJeffrey