[Backport main] Simplify ML processor form when interface is defined

[opensearch-trigger-bot]

Backport 47d59fe from #676.

[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/dashboards-flow-framework/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/dashboards-flow-framework/backport-2.x
# Create a new branch
git switch --create backport/backport-677-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 1ca0400b8f0be454dc2fd46747cb2332ca82d6b0
# Push it to GitHub
git push --set-upstream origin backport/backport-677-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/dashboards-flow-framework/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-677-to-2.x.