Add query group level rejection logic

[kaushalmahi12]

Description

With this change, we will be able to reject the requests for contended query groups.

Note

• The QueryGroupService is a stub here and will be replaced by the actual implementation in next couple of days
• Due to the above reason the tests for the QueryGroupService are intentionally left out to avoid the duplicate efforts.

Related Issues

RFC: #12342

Check List

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

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]

❌ Gradle check result for b583b61: 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 5811101: 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 c94f41e: 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 d51b251: 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 e29269e: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.backwards.MixedClusterClientYamlTestSuiteIT.test {p0=search.aggregation/360_date_histogram/Date histogram aggregation w/ shared field range test}

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 91.30435% with 2 lines in your changes missing coverage. Please review.

Project coverage is 71.98%. Comparing base (e146f13) to head (3cc8886).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...ain/java/org/opensearch/wlm/QueryGroupService.java	71.42%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #15428      +/-   ##
============================================
+ Coverage     71.92%   71.98%   +0.05%     
- Complexity    63483    63570      +87     
============================================
  Files          5244     5246       +2     
  Lines        296911   296930      +19     
  Branches      42879    42880       +1     
============================================
+ Hits         213557   213747     +190     
+ Misses        65799    65743      -56     
+ Partials      17555    17440     -115     

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[github-actions]

✅ Gradle check result for 768beeb: SUCCESS

[github-actions]

❌ Gradle check result for 5629506: 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 3cc8886: SUCCESS

[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-15428-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 c11d27575b87bd41f9e6512f48591ec0443eaf16
# Push it to GitHub
git push --set-upstream origin backport/backport-15428-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-15428-to-2.x.