[llvm] [LoopUtils] Fix metadata generated by makeFollowupLoopID (PR #131985)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

> If you fix it, could you fix it for wall followup_*?

Yes, of course, I was going to fix everything from the beginning (in that sense, I should have added more tests in #131337). Thanks also for the implementation advice.

https://github.com/llvm/llvm-project/pull/131985