Parallel test run

[bowenlan-amzn]

Issue #, if available:

Description of changes:

Follow up on #965, run ism and non-ism tests in parallel, now the tests running should finish within 20m

CheckList:

• 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.
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[codecov]

Codecov Report

Merging #966 (596ceaa) into main (12ab12f) will decrease coverage by 1.19%.
Report is 4 commits behind head on main.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main     #966      +/-   ##
============================================
- Coverage     75.72%   74.53%   -1.19%     
+ Complexity     2845     2774      -71     
============================================
  Files           364      364              
  Lines         16266    16266              
  Branches       2343     2343              
============================================
- Hits          12317    12124     -193     
- Misses         2607     2845     +238     
+ Partials       1342     1297      -45     

Files	Coverage Δ
...nt/indexstatemanagement/ManagedIndexCoordinator.kt	61.11% <100.00%> (-9.73%)	⬇️
...t/action/indexpolicy/TransportIndexPolicyAction.kt	80.95% <100.00%> (ø)
...rch/indexmanagement/snapshotmanagement/SMRunner.kt	65.21% <100.00%> (ø)
...gement/snapshotmanagement/engine/SMStateMachine.kt	75.00% <100.00%> (ø)

... and 27 files with indirect coverage changes

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/index-management/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/index-management/backport-2.x
# Create a new branch
git switch --create backport/backport-966-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 8b0cd6d4a4ed886c4dd009f845b61be26e0210f2
# Push it to GitHub
git push --set-upstream origin backport/backport-966-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/index-management/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-966-to-2.x.