[Remote Store] Do not trigger storeDirectory.sync in segment download flow from remote store

[sachinpkale]

Description

• As part of segment download from remote segment store, we fsync each downloaded segment file.
• fsync is not required as the segments are already present in remote store.
• Also, fsync will slow down the segment download flow.
• This was introduced in [Snapshot Interop] Add Changes in Restore Snapshot Flow for remote store Interoperability #6788

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)

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[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testDropPrimaryDuringReplication
      1 org.opensearch.index.IndexSettingsTests.testDefaultSearchPipelineWithoutFeatureFlag

• URL: https://build.ci.opensearch.org/job/gradle-check/20372/
• CommitID: 98c364d
  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 #8739 (98c364d) into main (164fbb1) will increase coverage by 0.21%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #8739      +/-   ##
============================================
+ Coverage     70.79%   71.01%   +0.21%     
- Complexity    57117    57231     +114     
============================================
  Files          4770     4770              
  Lines        270223   270222       -1     
  Branches      39493    39493              
============================================
+ Hits         191302   191893     +591     
+ Misses        62775    62145     -630     
- Partials      16146    16184      +38     

Impacted Files	Coverage Δ
...in/java/org/opensearch/index/shard/IndexShard.java	69.58% <ø> (+0.46%)	⬆️

... and 489 files with indirect coverage changes