Remove "Report abuse" button from a merged Merge Request

What does this MR do?

Removes "Report abuse" button from a merged Merge Request since the MR was already reviewed/approved/merged by maintainer(s).

Screenshots (strongly suggested)

Case	Before	After
Merged MR (PC)	TBD
Merged MR (mobile)	TBD
Open MR (PC)	TBD
Open MR (mobile)	TBD
Closed MR (PC)	TBD
Closed MR (mobile)	TBD
Open issue (PC) (no regression)	TBD
Open issue (mobile) (no regression)	TBD
Closed issue (PC) (no regression)	TBD
Closed issue (mobile) (no regression)	TBD

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Style guides
• Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Close #271589 (closed)