Remove group modal like remove project modal. Closes #33130

What does this MR do?

It changes the simple JS confirm to a safer modal, like when we confirm a project deletion.

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

I don't think so.

Why was this MR needed?

Safer deletion, richer/standard UI.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• 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?

#33130 (closed)