[llvm] [Utils] Identity map module-level debug info on first use in CloneFunction* (PR #118627)

[Felipe de Azevedo Piovezan via llvm-commits]

https://github.com/felipepiovezan commented:

Left some initial comments, but I would like to test this commit on the swift compiler, since it makes heavy use of metadata cloning and could reveal potential issues. I'll do this asap

https://github.com/llvm/llvm-project/pull/118627