Update spotless to meet JDK-21 baseline

[reta]

Is your feature request related to a problem? Please provide an existing Issue # , or describe. Add JDK-21 to Github actions

Describe the solution you are proposing A clear and concise description of what you want to happen.

Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered.

Additional context Add any other context or screenshots about the feature request here.

Check List

• [x] Backport Labels added.
• [x] New functionality includes testing.
  • [x] All tests pass
• [x] New functionality has been documented.
  • [ ] New functionality has javadoc added
• [x] 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.

[reta]

@ansjcy purely formatting updates (spotless update is needed to work with JDK-21)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (344cae1) 74.41% compared to head (4041830) 74.42%. Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #533 +/- ## ========================================= Coverage 74.41% 74.42% Complexity 2666 2666 ========================================= Files 317 317 Lines 16377 16377 Branches 1282 1282 ========================================= + Hits 12187 12188 +1 + Misses 3675 3674 -1 Partials 515 515 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[prudhvigodithi]

Looks like this is the change required for 2.12 builds to pass, https://github.com/opensearch-project/performance-analyzer/issues/611, can we please get this in soon and backport to 2.x?

[opensearch-trigger-bot[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-533-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 3c92f12e3ef0789bc7c7bda2a28b85a350008e80
# Push it to GitHub
git push --set-upstream origin backport/backport-533-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-533-to-2.x.