Add feature enable setting for controller index

[b4sjoo]

Description

This PR will add a feature enable setting for controller index, to support multi-tenancy

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

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[dhrubo-os]

Shouldn't we check this kind of places too:

ml-commons/plugin/src/main/java/org/opensearch/ml/model/MLModelManager.java

Line 1044 in b6618b2

deployControllerWithDeployingModel(mlModel, eligibleNodeCount);

[dhrubo-os]

@b4sjoo Any update on this?

[b4sjoo]

@b4sjoo Any update on this?

@dhrubo-os I don't think there are any blocking comments left, can we approve and merge it?

[dhrubo-os]

I haven't see any unit tests when controller is disabled for the transport actions. Can we add some tests accordingly?

[dhrubo-os]

Integration tests are failing. I retried now. I left few comments @b4sjoo

[b4sjoo]

I haven't see any unit tests when controller is disabled for the transport actions. Can we add some tests accordingly?

Fine I can add them when I get back. Not a hard job

[dhrubo-os]

I think we should also check here before performing deletion?

[b4sjoo]

I think we should also check here before performing deletion?

No need because it calls DeleteControllerTransportAction, which already have applied feature flag. No need to do the duplicated call.

[opensearch-trigger-bot]

The backport to feature/multi_tenancy 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-feature/multi_tenancy feature/multi_tenancy
# Navigate to the new working tree
cd .worktrees/backport-feature/multi_tenancy
# Create a new branch
git switch --create backport/backport-2652-to-feature/multi_tenancy
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 a72181a0fadd32dd16b7a84092dc2e7e2fc4d8b9
# Push it to GitHub
git push --set-upstream origin backport/backport-2652-to-feature/multi_tenancy
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-feature/multi_tenancy

Then, create a pull request where the base branch is feature/multi_tenancy and the compare/head branch is backport/backport-2652-to-feature/multi_tenancy.