[Backport 2.x] Fix Flaky TaskBatcherTests Tests

[opensearch-trigger-bot]

Backport 10fc755 from #12817.

[github-actions]

Compatibility status:

Checks if related components are compatible with change 5bae5c8

Incompatible components

Skipped components

Compatible components

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

[github-actions]

❌ Gradle check result for 5bae5c8: 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?

[dblock]

❌ Gradle check result for 5bae5c8: 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?

org.opensearch.backwards.MixedClusterClientYamlTestSuiteIT.test {p0=indices.get_field_mapping/20_missing_field/Return empty object if field doesn't exist, but index does}
org.opensearch.cluster.remote.test.RemoteClustersIT.testHAProxyModeConnectionWorks

#2440
#1703

[github-actions]

✅ Gradle check result for 5bae5c8: SUCCESS