[Backport 2.x] Add cluster manager throttling task stats in nodes stats API

[dhwanilpatel]

Description

Backport throttling stats PR to 2.x.

Original PR : https://github.com/opensearch-project/OpenSearch/pull/5790/commits

Issues Resolved

#479

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
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

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.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/9428/
• CommitID: ca77ad4
  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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/9430/
• CommitID: 692c3a0
  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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/9433/
• CommitID: 218de01
  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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/9434/
• CommitID: 269f62f
  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 (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/9445/
• CommitID: 20c1649

[codecov-commenter]

Codecov Report

Merging #5871 (20c1649) into 2.x (91cec04) will decrease coverage by 0.03%.
The diff coverage is 62.90%.

@@             Coverage Diff              @@
##                2.x    #5871      +/-   ##
============================================
- Coverage     70.48%   70.45%   -0.04%     
+ Complexity    58941    58889      -52     
============================================
  Files          4764     4764              
  Lines        282201   282257      +56     
  Branches      41108    41120      +12     
============================================
- Hits         198917   198856      -61     
- Misses        66691    66751      +60     
- Partials      16593    16650      +57     

Impacted Files	Coverage Δ
...min/cluster/stats/TransportClusterStatsAction.java	70.83% <ø> (ø)
.../org/opensearch/cluster/service/MasterService.java	84.26% <0.00%> (-0.23%)	⬇️
...search/cluster/MockInternalClusterInfoService.java	0.00% <0.00%> (ø)
.../java/org/opensearch/test/InternalTestCluster.java	57.64% <ø> (-1.29%)	⬇️
...src/main/java/org/opensearch/node/NodeService.java	72.13% <33.33%> (-0.76%)	⬇️
...rch/action/admin/cluster/node/stats/NodeStats.java	50.31% <44.44%> (-0.36%)	⬇️
...cluster/service/ClusterManagerThrottlingStats.java	74.50% <69.76%> (+4.50%)	⬆️
...on/admin/cluster/node/stats/NodesStatsRequest.java	68.04% <100.00%> (+0.33%)	⬆️
.../cluster/node/stats/TransportNodesStatsAction.java	100.00% <100.00%> (ø)
...port/ResponseHandlerFailureTransportException.java	0.00% <0.00%> (-60.00%)	⬇️
... and 476 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.