[llvm] [Transforms][Utils] Preserve branch weights in LoopSplitUtils (PR #213626)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

> It was an urgent fix as buildbots were failing, and the test has been added as a follow-up: https://github.com/llvm/llvm-project/pull/213647.

In that case, reverting is usually a safe option as well

https://github.com/llvm/llvm-project/pull/213626