[llvm] [IndVarSimplify] Fix `IndVarSimplify` to skip on unfolding predicates when the loop contains control convergence operations. (PR #165643)

[Nathan Gauër via llvm-commits]

https://github.com/Keenuts approved this pull request.

OK for the code change in the pass. Same remarks as Steven for tests: you shld only have simple functions in those tests and remove all HLSL-specific bits & unnecessary attributes etc

https://github.com/llvm/llvm-project/pull/165643