[Backport 2.17] Provide factory for pluggable deciders

[Gankris96]

Description

Backport of #15713

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

❕ Gradle check result for 6879c30: UNSTABLE

• TEST FAILURES:

      2 org.opensearch.smoketest.SmokeTestMultiNodeClientYamlTestSuiteIT.test {yaml=search.aggregation/360_date_histogram/Date histogram aggregation w/ shared field range test}
      1 org.opensearch.snapshots.DedicatedClusterSnapshotRestoreIT.testSnapshotWithStuckNode

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[codecov]

Codecov Report

Attention: Patch coverage is 90.47619% with 2 lines in your changes missing coverage. Please review.

Project coverage is 71.70%. Comparing base (75fb5bc) to head (b318c6a).
Report is 5 commits behind head on 2.17.

Files with missing lines	Patch %	Lines
...earch/deciders/ConcurrentSearchRequestDecider.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               2.17   #15734      +/-   ##
============================================
+ Coverage     71.66%   71.70%   +0.03%     
- Complexity    64317    64431     +114     
============================================
  Files          5262     5263       +1     
  Lines        301148   301180      +32     
  Branches      43841    43846       +5     
============================================
+ Hits         215829   215960     +131     
+ Misses        67259    67144     -115     
- Partials      18060    18076      +16     

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[github-actions]

✅ Gradle check result for 2ec900a: SUCCESS

[github-actions]

❌ Gradle check result for b318c6a: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[jed326]

https://build.ci.opensearch.org/job/gradle-check/47252/

• [BUG] org.opensearch.search.basic.SearchWithRandomExceptionsIT.testRandomExceptions {p0={"search.concurrent_segment_search.enabled":"false"}} if flaky #13846

[github-actions]

✅ Gradle check result for b318c6a: SUCCESS