Revoke button in Applications Settings underlines on hover

What does this MR do?

Removes the btn-link class from the "Revoke" button

Why was this MR needed?

The button was being underlined on hover and it shouldn't.

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

fixes #18932 (closed)