Refactor the merge section of the merge request widget
- gitlab-ce!20189 (merged) introduced a new design for the werge request widget info and pipeline sections
#5927 (closed) introduces a new design for the middle (report) part of the mr widget. Included in the mockups is an indication of how the bottom part (in order to get the mr merged) is going to look like.
This redesign is preferably needed in order to support #3709 (closed)