[llvm] [MachinePipeliner] Remove isLoopCarriedDep and use DDG (PR #174394)

[Ankit Aggarwal via llvm-commits]

https://github.com/aankit-ca approved this pull request.

Sorry, I completely forgot about this patch. The change does look correct to me. Let's merge this and I can get back to you if we see any failures once this patch lands downstream.

https://github.com/llvm/llvm-project/pull/174394