[Remote Store] Add support to disable flush based on translog reader count

[shourya035]

Description

We introduced ability to run flush automatically based on the number of accumulated translog readers. With this PR, we are -1 as a permissible value for the setting cluster.remote_store.translog.max_readers which would disable this feature.

This is needed to prevent repeated flushes when a large number of translog files get accumulated, especially when a shard copy is relocating to another node and the active primary is getting large number of writes. This also helps during the remotestore migration when the remote seeding process ends up accumulating a lot of translog on the active primary which needs to be replayed after the seeding process is complete.

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 5679151: 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 4d77837: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 71.58%. Comparing base (b15cb0c) to head (4d77837).
Report is 355 commits behind head on main.

❗ Current head 4d77837 differs from pull request most recent head 75e28a9

Please upload reports for the commit 75e28a9 to get more accurate results.

Files	Patch %	Lines
...rg/opensearch/index/translog/RemoteFsTranslog.java	25.00%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #14027      +/-   ##
============================================
+ Coverage     71.42%   71.58%   +0.16%     
- Complexity    59978    61368    +1390     
============================================
  Files          4985     5071      +86     
  Lines        282275   288396    +6121     
  Branches      40946    41766     +820     
============================================
+ Hits         201603   206459    +4856     
- Misses        63999    64888     +889     
- Partials      16673    17049     +376     

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[astute-decipher]

Changes LGTM.

[github-actions]

❕ Gradle check result for 75e28a9: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.gateway.RecoveryFromGatewayIT.testShardStoreFetchMultiNodeMultiIndexesUsingBatchAction

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

[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-14027-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 b9ca5a8e24673ed38cab736ffbd57479de241553
# Push it to GitHub
git push --set-upstream origin backport/backport-14027-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-14027-to-2.x.