Address feedback from rolling out vue refactor of MR List

Context

Rollout for the &10827 (closed) has begun in 17.6 and we expect some potential feedback that need to be address during 17.7 to enable the FF by default.

This issue is a buffer to save capacity for this work.

Tasks

Check the child items in this issue:

• Recover the MERGED popover on the vue MR list (#504636 - closed)
• Scoped labels are broken in the vue MR list (#505340 - closed)