[Backport 2.x] SegRep with Remote: Add hook for publishing checkpoint notifications after segment upload to remote store (#7394)

[ashking94]

• SegRep with Remote: Add hook for publishing checkpoint notifications after segment upload to remote store

• Added changelog

• Fix the test

• gradle check

• Addressed PR comments

• Addressing PR comments 2

• Addressed comments 3

• Fix Changelog entry

---

Description

This backports #7394

Related Issues

Resolves #5578

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.search.SearchWeightedRoutingIT.testStrictWeightedRoutingWithCustomString

• URL: https://build.ci.opensearch.org/job/gradle-check/16153/
• CommitID: 61ab7b2
  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 #7718 (61ab7b2) into 2.x (636e772) will increase coverage by 0.07%.
The diff coverage is 71.42%.

@@             Coverage Diff              @@
##                2.x    #7718      +/-   ##
============================================
+ Coverage     70.53%   70.60%   +0.07%     
- Complexity    56370    56408      +38     
============================================
  Files          4663     4663              
  Lines        267521   267530       +9     
  Branches      39612    39616       +4     
============================================
+ Hits         188701   188897     +196     
+ Misses        62604    62332     -272     
- Partials      16216    16301      +85     

Impacted Files	Coverage Δ
.../main/java/org/opensearch/index/IndexSettings.java	85.35% <0.00%> (-0.44%)	⬇️
...in/java/org/opensearch/index/shard/IndexShard.java	70.35% <66.66%> (+0.13%)	⬆️
...nsearch/index/shard/CheckpointRefreshListener.java	91.66% <75.00%> (-8.34%)	⬇️
...search/index/shard/RemoteStoreRefreshListener.java	81.56% <100.00%> (-0.33%)	⬇️

... and 460 files with indirect coverage changes