Fix flaky test for CopyProcessorTests

[gaobinlong]

Description

Flaky test found in org.opensearch.ingest.common.CopyProcessorTests.testCopyToExistingField, the reason is that when one filed to another, we use deepCopy, if the copied object is a map and its value is array, the equalTo assertion in CopyProcessorTests will fail, we should handle this case correctly. I've added a new assert method to handle that case, the code are inspired by here..

Ran 1000 times in my local env with this change, never reproduce again.

Related Issues

#11974

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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[gaobinlong]

Hi @reta , please help to review this PR, and skip-changelog label is needed, please help to add, thanks!

[github-actions]

Compatibility status:

Checks if related components are compatible with change acb34b9

Incompatible components

Incompatible components: [https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/performance-analyzer.git, https://github.com/opensearch-project/performance-analyzer-rca.git, https://github.com/opensearch-project/custom-codecs.git, https://github.com/opensearch-project/sql.git, https://github.com/opensearch-project/cross-cluster-replication.git]

Skipped components

Compatible components

Compatible components: [https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/reporting.git, https://github.com/opensearch-project/job-scheduler.git, https://github.com/opensearch-project/k-nn.git, https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/index-management.git, https://github.com/opensearch-project/notifications.git, https://github.com/opensearch-project/opensearch-oci-object-storage.git, https://github.com/opensearch-project/neural-search.git, https://github.com/opensearch-project/anomaly-detection.git, https://github.com/opensearch-project/geospatial.git, https://github.com/opensearch-project/ml-commons.git, https://github.com/opensearch-project/alerting.git, https://github.com/opensearch-project/security.git]

[github-actions]

❌ Gradle check result for acb34b9: null

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 acb34b9: UNSTABLE

• TEST FAILURES:

      2 org.opensearch.index.shard.RemoteStoreRefreshListenerTests.classMethod
      1 org.opensearch.index.shard.RemoteStoreRefreshListenerTests.testRefreshAfterCommit

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[reta]

Thanks @gaobinlong !