Change priority for scheduling reroute during timeout

[imRishN]

Description

This PR updates the priority of scheduling reroute when timed out from HIGH to NORMAL. This is because consistent HIGH reroutes might starve NORMAL priority tasks. And moreover, NORMAL is right for reasonable clusters. For clusters in messed up state which is causing NORMAL priority tasks to starve, we add a new dynamic cluster setting to raise the priority of reroute task to allocate shards in such scenarios.

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• [ ] Functionality includes testing.
• [ ] API changes companion pull request created, if applicable.
• [ ] Public documentation issue/PR created, if applicable.

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[github-actions]

❌ Gradle check result for 5e83a92: 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?

[Bukhtawar]

Lets update the PR description

[imRishN]

Lets update the PR description

Updated

[github-actions]

❌ Gradle check result for 6a448d0: FAILURE

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[github-actions]

❌ Gradle check result for f29d380: FAILURE

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[github-actions]

❌ Gradle check result for 57a8686: FAILURE

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[github-actions]

❌ Gradle check result for 57a8686: 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?

[github-actions]

❌ Gradle check result for 57a8686: 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?

[github-actions]

❌ Gradle check result for 4696885: FAILURE

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[github-actions]

✅ Gradle check result for 614f75b: SUCCESS

[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/OpenSearch/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch/backport-2.x
# Create a new branch
git switch --create backport/backport-16445-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 36d798cc42c473bdb49f4bf39093dd3dd9191b70
# Push it to GitHub
git push --set-upstream origin backport/backport-16445-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-16445-to-2.x.

[github-actions]

❌ Gradle check result for 57a8686: 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?