Adds release notes for 2.1.0 and revert #1890

[DarshitChanpura]

Description

• Category - Maintenance

Check List

• New functionality includes testing
• New functionality has been documented
• Commits are signed per the DCO using --signoff

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.

[codecov-commenter]

Codecov Report

Merging #1901 (f171d63) into main (d507ebb) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #1901      +/-   ##
============================================
- Coverage     61.00%   60.95%   -0.06%     
+ Complexity     3234     3232       -2     
============================================
  Files           256      256              
  Lines         18088    18087       -1     
  Branches       3224     3224              
============================================
- Hits          11035    11025      -10     
- Misses         5470     5478       +8     
- Partials       1583     1584       +1     

Impacted Files	Coverage Δ
...org/opensearch/security/rest/TenantInfoAction.java	77.94% <0.00%> (-10.30%)	⬇️
...ecurity/ssl/rest/SecuritySSLReloadCertsAction.java	84.78% <0.00%> (-0.33%)	⬇️
...a/org/opensearch/security/tools/SecurityAdmin.java	37.31% <0.00%> (-0.25%)	⬇️

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[cliu123]

Converting the draft to an open PR for review.

[peternied]

@DarshitChanpura Could you rebase with main, it will use the latest version of the tests that should clear up the intermittent failures

[DarshitChanpura]

@DarshitChanpura Could you rebase with main, it will use the latest version of the tests that should clear up the intermittent failures

Done.. @cliu123 can you please re-review this PR

[cliu123]

@DarshitChanpura Why this release notes PR includes other changes? If those changes have been merged, please rebase this branch. The PR has been merged, so the changes are not supposed to show as diff in this branch if this branch gets updated changes in main branch.

[DarshitChanpura]

I have reverted the version bump PR: #1890 commit due to issue #1918

[DarshitChanpura]

@opensearch-project/security Can I get reviews for this?

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 1

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
cd .worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-1901-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 15f1fbd6191dc3a80eda02ba2e2a1b835f57db88
# Push it to GitHub
git push --set-upstream origin backport/backport-1901-to-2.x
# Go back to the original working tree
cd ../..
# 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-1901-to-2.x.