Revert "Searchbackpressure Service Reader and UTs added (#427) (#495)"

[khushbr]

This reverts commit aef3981.

1st of 3 part change to revert Search BackPressure changes, the changes can be added later once the core change opensearch-project/OpenSearch#10028 is merged.

Check List

• Backport Labels added.
• 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 #504 (faa00df) into 2.x (815ac0a) will decrease coverage by 0.34%.
The diff coverage is n/a.

❗ Current head faa00df differs from pull request most recent head 84da32f. Consider uploading reports for the commit 84da32f to get more accurate results

@@             Coverage Diff              @@
##                2.x     #504      +/-   ##
============================================
- Coverage     74.46%   74.12%   -0.34%     
+ Complexity     2666     2639      -27     
============================================
  Files           317      315       -2     
  Lines         16298    16077     -221     
  Branches       1277     1271       -6     
============================================
- Hits          12136    11917     -219     
+ Misses         3652     3649       -3     
- Partials        510      511       +1     

Files	Coverage Δ
...eanalyzer/rca/framework/metrics/ReaderMetrics.java	97.50% <ø> (-0.07%)	⬇️
...rch/performanceanalyzer/reader/MetricsEmitter.java	95.64% <ø> (+0.81%)	⬆️
...ormanceanalyzer/reader/ReaderMetricsProcessor.java	78.71% <ø> (-0.62%)	⬇️

... and 4 files with indirect coverage changes