[llvm] [AMDGPU][SIPreEmitPeephole] mustRetainExeczBranch: use BranchProbability and TargetSchedmodel (PR #109818)

[Juan Manuel Martinez Caamaño via llvm-commits]

jmmartinez wrote:

The windows buildbot yielded some strange results. While the Linux buildbot succeeded, the Windows one failed for tests that are supposed to be independent from the host.

https://github.com/llvm/llvm-project/pull/109818