Improve error messages for _stats with closed indices (#13012)

[srikanthpadakanti]

• Improve the error messages for _stats with closed indices

Signed-off-by: srikanth padakanti srikanth29.9@gmail.com

---

Signed-off-by: Srikanth Padakanti srikanth29.9@gmail.com
(cherry picked from commit 98009ed)

Description

Improve the error messages for _stats with closed indices

Related Issues

Resolves #[https://github.com//issues/11180]

Check List

• [ X] New functionality includes testing.
  • [ X] All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• [ X] Commits are signed per the DCO using --signoff
• [ X] Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• [ X] Public documentation issue/PR created

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[github-actions]

❕ Gradle check result for 910c66c: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.remotestore.RemoteStoreStatsIT.testNonZeroPrimaryStatsOnNewlyCreatedIndexWithZeroDocs
      1 org.opensearch.backwards.MixedClusterClientYamlTestSuiteIT.test {p0=indices.get_field_mapping/20_missing_field/Return empty object if field doesn't exist, but index does}

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

Attention: Patch coverage is 75.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 71.07%. Comparing base (0dd892c) to head (910c66c).
Report is 164 commits behind head on 2.x.

Files	Patch %	Lines
.../cluster/metadata/IndexNameExpressionResolver.java	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #13338      +/-   ##
============================================
- Coverage     71.28%   71.07%   -0.22%     
- Complexity    60145    60566     +421     
============================================
  Files          4957     5005      +48     
  Lines        282799   285471    +2672     
  Branches      41409    41737     +328     
============================================
+ Hits         201591   202896    +1305     
- Misses        64189    65434    +1245     
- Partials      17019    17141     +122     

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