Revert "Clean up temporary files created during segment merge incase …

[RS146BIJAY]

…segment merge fails"

This reverts commit d15e628.

Description

Reverting the commit to delete temp files incase segment merge fails. The flush call was failing incase Lucene closes the IndexWriter before the call. Will re raise the PR for this fix after handling all the race condition scenarioes correctly.

Issues Resolved

#5710

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: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/11471/
• CommitID: 90276a6
  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 (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/11472/
• CommitID: d46d729

[codecov-commenter]

Codecov Report

Merging #6403 (d46d729) into main (72314f7) will increase coverage by 0.12%.
The diff coverage is n/a.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

@@             Coverage Diff              @@
##               main    #6403      +/-   ##
============================================
+ Coverage     70.62%   70.74%   +0.12%     
- Complexity    58930    59047     +117     
============================================
  Files          4799     4799              
  Lines        282440   282439       -1     
  Branches      40719    40719              
============================================
+ Hits         199477   199821     +344     
+ Misses        66580    66210     -370     
- Partials      16383    16408      +25     

Impacted Files	Coverage Δ
...va/org/opensearch/index/engine/InternalEngine.java	75.41% <ø> (+0.13%)	⬆️
...java/org/opensearch/client/indices/DataStream.java	0.00% <0.00%> (-76.09%)	⬇️
...pensearch/client/cluster/RemoteConnectionInfo.java	0.00% <0.00%> (-73.18%)	⬇️
.../opensearch/client/indices/CloseIndexResponse.java	17.50% <0.00%> (-60.00%)	⬇️
...a/org/opensearch/client/cluster/ProxyModeInfo.java	0.00% <0.00%> (-55.00%)	⬇️
...a/org/opensearch/client/cluster/SniffModeInfo.java	0.00% <0.00%> (-52.95%)	⬇️
...h/action/ingest/SimulateDocumentVerboseResult.java	60.71% <0.00%> (-39.29%)	⬇️
.../opensearch/client/cluster/RemoteInfoResponse.java	61.53% <0.00%> (-38.47%)	⬇️
...cluster/coordination/PublishClusterStateStats.java	33.33% <0.00%> (-37.51%)	⬇️
...nsearch/index/shard/IndexShardClosedException.java	66.66% <0.00%> (-33.34%)	⬇️
... and 475 more

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[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-6403-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 87bdd0806b77ea4c0ae1eed6830fd1570abd36f6
# Push it to GitHub
git push --set-upstream origin backport/backport-6403-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-6403-to-2.x.