[llvm] [AMDGPU] AMDGPULateCodeGenPrepare Legacy PM: replace `setPreservesAll()` with `setPreservesCFG()` (PR #148167)

[Jim M. R. Teichgräber via llvm-commits]

J-MR-T wrote:

(Now the first 3 commits belong to the dependent PR #148165, because of review changes there)

https://github.com/llvm/llvm-project/pull/148167