What does this MR do?
- In the MR Widget, when user can't remove source branch, we hide the checkbox
- In the MR Create/Edit View, when user can't remove source branch, we hide the checkbox
- In the MR Widget, when the user can't remove the source branch and the source branch will be removed, show a message in the MR Widget that says "Removes source branch".
- Update existing specs and add new ones for the "Removes source branch" status message
- Adds some logic to the spec helper method
mountComponentto support passing plain Vue config objects
Are there points in the code the reviewer needs to double check?
Why was this MR needed?
Screenshots (if relevant)
Does this MR meet the acceptance criteria?
Changelog entry added, if necessary
API support added
Tests added for this feature/bug
Has been reviewed by UX
Has been reviewed by Frontend
Has been reviewed by Backend
Has been reviewed by Database
Conform by the merge request performance guides
Conform by the style guides
Squashed related commits together
What are the relevant issue numbers?
Closes #33264 (moved)