[llvm] [RemoveDIs] Fix remapping of DbgLabelRecords. (PR #91447)

[Harald van Dijk via llvm-commits]

hvdijk wrote:

I also have a followup patch, https://github.com/hvdijk/llvm-project/commit/removedis-fix-2, that I think GitHub does not let me create a PR for in a readable way until this goes in.

Both this and the other one are because we were seeing in downstream code that `CloneModule` mishandles modules containing `#dbg_label` that would show up now that 91446e2aa687ec57ad88dc0df793d0c6e694a7c9 has been pushed.

https://github.com/llvm/llvm-project/pull/91447