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

[Harald van Dijk via llvm-commits]

hvdijk wrote:

My colleague has a test case that constructs a module, asserts that it passes verification, clones it, and checks that the clone also passes verification (a test which fails, but passes once both commits are applied). It probably needs a bit further reduction, and the test won't pass just after this PR, it will only start passing when the other commit is also in. Is it okay with you to add the test afterwards?

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