stash thread context before running forward action

[ylwu-amzn]

Description

[Describe what this change achieves]

Issues Resolved

[List any issues this PR will resolve]

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

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.

[codecov]

Codecov Report

Attention: 12 lines in your changes are missing coverage. Please review.

Comparison is base (54c788a) 82.61% compared to head (cf7243c) 82.62%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
...ction/deploy/TransportDeployModelOnNodeAction.java	0.00%	8 Missing ⚠️
.../java/org/opensearch/ml/utils/RestActionUtils.java	75.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1904   +/-   ##
=========================================
  Coverage     82.61%   82.62%           
- Complexity     5383     5388    +5     
=========================================
  Files           521      521           
  Lines         21715    21727   +12     
  Branches       2210     2211    +1     
=========================================
+ Hits          17940    17952   +12     
+ Misses         2878     2875    -3     
- Partials        897      900    +3     

Flag	Coverage Δ
ml-commons	82.62% <50.00%> (+<0.01%)	⬆️

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[mingshl]

This change should fix the issue when multiple threads running in progress.

[opensearch-trigger-bot]

The backport to 2.9 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.9 2.9
# Navigate to the new working tree
cd .worktrees/backport-2.9
# Create a new branch
git switch --create backport/backport-1904-to-2.9
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 a14521dd97397c2ec9f6899e5d7d2f450986a5f9
# Push it to GitHub
git push --set-upstream origin backport/backport-1904-to-2.9
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.9

Then, create a pull request where the base branch is 2.9 and the compare/head branch is backport/backport-1904-to-2.9.