chore: Use create branch component for convert_to_gitlab_ci flow

What does this merge request do and why?

Add branch creation to the convert to gitlab ci flow

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Set up Duo Agent Platform
2. Run a Convert to GitLab CI Flow
3. Check the created branch name in the flow

Example langsmith trace (internal)

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.
• If this change requires executor implementation: verified that issues/MRs exist for both Go executor and Node executor or confirmed that changes are backward-compatible and don't break existing executor functionality.