Add generic auto merge system notes
What does this MR do and why?
We are going to be doing a refactor of the Merge When Checks Pass. The draft MR for this refactor is: !145113 (closed). We are going to be splitting this MR into pieces to make it easier to review.
The second step is to add a new more generic auto merge system notes to replace merge when pipeline succeed notes.
Edited by Marc Shaw