Popover for default approval rule not showing

Summary

Was not fixed in !15378 (merged) per the original issue's requirements (#13215 (closed)).

When hovering or clicking the question mark icon next to the default approval rule (“Any eligible user”), nothing happens. According to #13215 (closed), a popover should appear, explaining who is an eligible approver.

Steps to reproduce

1. Navigate to General project settings
2. Expand the Merge request approvals section
3. Attempt to click or hover the question mark icon next to the default approval rule (“Any eligible user”)

Relevant logs and/or screenshots

Dec-04-2019_10-52-56