style links on system notes to look clickable

What does this MR do?

Make Compare with previous version and Toggle commit list look like links

Are there points in the code the reviewer needs to double check?

After clicking Toggle commit list the hover style is still applied until mouse moves. Not related to this though

Why was this MR needed?

Didn't look clickable before

Screenshots (if relevant)

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 it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #27959 (closed)