Sort referenced issues numerically

What does this MR do and why?

Sort referenced issues numerically (and still locally)

Merge request-related "mentioned issues" should... (#29307 - closed)

What does this MR not do?

I think if you reference issues from different groups, those should come after the issues referenced issues in different projects but the same group (if that makes any sense). This isn't the case on master, or in this MR

Screenshots or screen recordings

Before	After

How to set up and validate locally

• Mention multiple issues in a merge request that previously were ordered alphabetically (ie 10, 2, 9)
• Mention issues from different project
• Issues should be ordered first locally and numerically, then by other projects

UX Paper Cuts 16.3 → Settings UI, part 2 (#417912 - closed)