[Backport 2.x] [Sort] Sending missing values in comparator instead sending null

[gashutos]

Backport of #11196

Description

[Describe what this change achieves]

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• New functionality includes testing.
  • 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)
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• Public documentation issue/PR created

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For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

Compatibility status:

Checks if related components are compatible with change 500a7d3

Incompatible components

Incompatible components: [https://github.com/opensearch-project/performance-analyzer.git, https://github.com/opensearch-project/k-nn.git]

Skipped components

Compatible components

Compatible components: [https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/reporting.git, https://github.com/opensearch-project/custom-codecs.git, https://github.com/opensearch-project/job-scheduler.git, https://github.com/opensearch-project/performance-analyzer-rca.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/notifications.git, https://github.com/opensearch-project/anomaly-detection.git, https://github.com/opensearch-project/ml-commons.git, https://github.com/opensearch-project/neural-search.git, https://github.com/opensearch-project/index-management.git, https://github.com/opensearch-project/security.git, https://github.com/opensearch-project/alerting.git, https://github.com/opensearch-project/geospatial.git, https://github.com/opensearch-project/cross-cluster-replication.git, https://github.com/opensearch-project/sql.git]

[github-actions]

❌ Gradle check result for 3220bc7: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❕ Gradle check result for 500a7d3: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.action.admin.cluster.node.tasks.ResourceAwareTasksTests.testTaskResourceTrackingDuringTaskCancellation

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: 6 lines in your changes are missing coverage. Please review.

Comparison is base (3cc2e54) 70.79% compared to head (500a7d3) 70.82%.
Report is 5 commits behind head on 2.x.

Files	Patch %	Lines
.../fieldcomparator/DoubleValuesComparatorSource.java	0.00%	0 Missing and 1 partial ⚠️
...a/fieldcomparator/FloatValuesComparatorSource.java	0.00%	0 Missing and 1 partial ⚠️
...eldcomparator/HalfFloatValuesComparatorSource.java	0.00%	1 Missing ⚠️
...ata/fieldcomparator/IntValuesComparatorSource.java	0.00%	0 Missing and 1 partial ⚠️
...ta/fieldcomparator/LongValuesComparatorSource.java	0.00%	0 Missing and 1 partial ⚠️
...comparator/UnsignedLongValuesComparatorSource.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #11250      +/-   ##
============================================
+ Coverage     70.79%   70.82%   +0.02%     
- Complexity    58873    58947      +74     
============================================
  Files          4867     4867              
  Lines        278455   278455              
  Branches      40810    40810              
============================================
+ Hits         197140   197205      +65     
+ Misses        64524    64521       -3     
+ Partials      16791    16729      -62     

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[gashutos]

@dblock Lets merge this ?