Capture diff note position on mergeability check
What does this MR do?
When a merge request is checked whether it's mergeable merge_ref_head is updated and we need to update diff note positions within it.
Related issue: #198457 (closed)
Related MRs:
-
!28113 (merged) - Introduces
diff_note_positionstable - !28003 (closed) - draft MR for demonstrating the general idea
Edited by Igor Drozdov