Added validation for the new clusters field.

[AWSHurneyt]

Description

1. Added validation for the clusters field.
2. Refactored ClusterMetricsInput validiation to throw 4xx-level CommonUtilsExceptions instead of 5xx-level IllegalArgumentException.

Issues Resolved

[List any issues this PR will resolve]

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

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.

[AWSHurneyt]

Whitesource finding will be fixed in a separate PR.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 20 lines in your changes are missing coverage. Please review.

Project coverage is 73.73%. Comparing base (c05715b) to head (4636569).

❗ Current head 4636569 differs from pull request most recent head 89aef1c. Consider uploading reports for the commit 89aef1c to get more accurate results

Files	Patch %	Lines
...arch/commons/alerting/util/CommonUtilsException.kt	39.28%	11 Missing and 6 partials ⚠️
...org/opensearch/commons/alerting/util/IndexUtils.kt	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #633      +/-   ##
============================================
- Coverage     73.90%   73.73%   -0.17%     
  Complexity      891      891              
============================================
  Files           133      134       +1     
  Lines          5870     5910      +40     
  Branches        717      726       +9     
============================================
+ Hits           4338     4358      +20     
- Misses         1219     1233      +14     
- Partials        313      319       +6     

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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:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/common-utils/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/common-utils/backport-2.x
# Create a new branch
git switch --create backport-633-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 abc69cdbaf1de6258db430b1d284e7a3e614c83b
# Push it to GitHub
git push --set-upstream origin backport-633-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/common-utils/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport-633-to-2.x.

[opensearch-trigger-bot]

The backport to 2.12 failed:

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

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/common-utils/backport-2.12 2.12
# Navigate to the new working tree
pushd ../.worktrees/common-utils/backport-2.12
# Create a new branch
git switch --create backport-633-to-2.12
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 abc69cdbaf1de6258db430b1d284e7a3e614c83b
# Push it to GitHub
git push --set-upstream origin backport-633-to-2.12
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/common-utils/backport-2.12

Then, create a pull request where the base branch is 2.12 and the compare/head branch is backport-633-to-2.12.

[opensearch-trigger-bot]

The backport to 2.13 failed:

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

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/common-utils/backport-2.13 2.13
# Navigate to the new working tree
pushd ../.worktrees/common-utils/backport-2.13
# Create a new branch
git switch --create backport-633-to-2.13
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 abc69cdbaf1de6258db430b1d284e7a3e614c83b
# Push it to GitHub
git push --set-upstream origin backport-633-to-2.13
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/common-utils/backport-2.13

Then, create a pull request where the base branch is 2.13 and the compare/head branch is backport-633-to-2.13.