Align range and default value for deletes_pct_allowed in merge policy

[nkumar04]

Adjust the range and default value for deletes_pct_allowed in merge policy for more control and optimal disk usage (#7360)

Description

This change is to align the default value of deletesPctAllowed in merge policy with Lucene. This change will help in optimal usage of disk and reduce the deleted docs in an index. Search performance would also be better if there are less deleted docs in an index.

Related Issues

Resolves #7360

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]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.cluster.allocation.AwarenessAllocationIT.testThreeZoneOneReplicaWithForceZoneValueAndLoadAwareness

• URL: https://build.ci.opensearch.org/job/gradle-check/16194/
• CommitID: ecb5d6c
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.search.backpressure.SearchBackpressureIT.testSearchTaskCancellationWithHighCpu

• URL: https://build.ci.opensearch.org/job/gradle-check/16193/
• CommitID: bcf41b0
  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

Merging #7730 (29c018e) into main (8773509) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #7730      +/-   ##
============================================
- Coverage     70.88%   70.85%   -0.04%     
+ Complexity    56352    56339      -13     
============================================
  Files          4700     4700              
  Lines        266549   266549              
  Branches      39099    39099              
============================================
- Hits         188937   188856      -81     
- Misses        61632    61723      +91     
+ Partials      15980    15970      -10     

Impacted Files	Coverage Δ
...n/java/org/opensearch/index/MergePolicyConfig.java	74.66% <ø> (ø)

... and 461 files with indirect coverage changes

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.search.backpressure.SearchBackpressureIT.testSearchShardTaskCancellationWithHighCpu

• URL: https://build.ci.opensearch.org/job/gradle-check/17005/
• CommitID: 29c018e
  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:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-7730-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 9b2b3c94728bc7f5f3771b440245a55341940a38
# Push it to GitHub
git push --set-upstream origin backport/backport-7730-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-7730-to-2.x.