Route search traffic to _primary_first for warm index

[neetikasinghal]

Description

Route search traffic to _primary_first for warm index

Related Issues

Resolves #14543

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 26d05fa: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.repositories.azure.AzureBlobContainerRetriesTests.testWriteLargeBlob

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 60.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 71.85%. Comparing base (087355f) to head (26d05fa).

Files	Patch %	Lines
...g/opensearch/cluster/routing/OperationRouting.java	60.00%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #14934      +/-   ##
============================================
+ Coverage     71.79%   71.85%   +0.05%     
- Complexity    62598    62665      +67     
============================================
  Files          5159     5159              
  Lines        294036   294041       +5     
  Branches      42515    42518       +3     
============================================
+ Hits         211104   211282     +178     
+ Misses        65528    65370     -158     
+ Partials      17404    17389      -15     

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[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 1

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-14934-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 0324edda286a2ab8a795d7f86b3402d229cd2255
# Push it to GitHub
git push --set-upstream origin backport/backport-14934-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-14934-to-2.x.