[llvm] [LICM] Use DomTreeUpdater version of SplitBlockPredecessors, nfc (PR #107190)

[Joshua Cao via llvm-commits]

caojoshua wrote:

I completed reworked this patch. I found the root cause of the bugs after modifying LICM to use the DTU version of SplitBlockPredecessors was that we were iterating over DomTreeNodes while updating the DomTree at the same time. I updated the main PR post.

https://github.com/llvm/llvm-project/pull/107190