Refactored the RSA to make it more extensible

[shiv0408]

Description

In this PR, we are refactoring the ReplicaShardAllocator code to make it more reusable as we bring in Batch Allocator in #8992.

We have broken this function to multiple functions, so that part of codes can be reused and only a single function need to be overwritten in child class to implement the Batch allocator.

OpenSearch/server/src/main/java/org/opensearch/gateway/ReplicaShardAllocator.java

Lines 179 to 183 in 8807d7a

	public AllocateUnassignedDecision makeAllocationDecision(
	final ShardRouting unassignedShard,
	final RoutingAllocation allocation,
	final Logger logger
	) {

We have also created NodeShardStore and NodeShardStores to encapsulate the data that needs to be passed around in these functions.

Related Issues

Resolves #8960

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
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

Compatibility status:

Checks if related components are compatible with change e2e8f38

Incompatible components

Skipped components

Compatible components

Compatible components: [https://github.com/opensearch-project/custom-codecs.git, https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/neural-search.git, https://github.com/opensearch-project/flow-framework.git, https://github.com/opensearch-project/cross-cluster-replication.git, https://github.com/opensearch-project/reporting.git, https://github.com/opensearch-project/job-scheduler.git, https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/geospatial.git, https://github.com/opensearch-project/opensearch-oci-object-storage.git, https://github.com/opensearch-project/notifications.git, https://github.com/opensearch-project/k-nn.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/anomaly-detection.git, https://github.com/opensearch-project/ml-commons.git, https://github.com/opensearch-project/alerting.git, https://github.com/opensearch-project/index-management.git, https://github.com/opensearch-project/performance-analyzer-rca.git, https://github.com/opensearch-project/sql.git, https://github.com/opensearch-project/security.git, https://github.com/opensearch-project/performance-analyzer.git]

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/26384/
• CommitID: f08531c
  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?

[shwetathareja]

It is failing during build as it has dependency on other PR for merge.

[github-actions]

❌ Gradle check result for c7d1b88: 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?

[github-actions]

✅ Gradle check result for e2e8f38: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 69.86301% with 22 lines in your changes are missing coverage. Please review.

Project coverage is 71.41%. Comparing base (b15cb0c) to head (e2e8f38).
Report is 27 commits behind head on main.

Files	Patch %	Lines
.../org/opensearch/gateway/ReplicaShardAllocator.java	69.86%	8 Missing and 14 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #10254      +/-   ##
============================================
- Coverage     71.42%   71.41%   -0.01%     
- Complexity    59978    60118     +140     
============================================
  Files          4985     4991       +6     
  Lines        282275   282635     +360     
  Branches      40946    40990      +44     
============================================
+ Hits         201603   201846     +243     
- Misses        63999    64067      +68     
- Partials      16673    16722      +49     

☔ View full report in Codecov by Sentry.
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[shiv0408]

Thanks for the approval @shwetathareja!

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/OpenSearch/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch/backport-2.x
# Create a new branch
git switch --create backport/backport-10254-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 3a9c20ba394121e73226b48d3e46bf3104a2bde7
# Push it to GitHub
git push --set-upstream origin backport/backport-10254-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-10254-to-2.x.