[clang] [CIR] Fix building ClangIR after RegionBranchOpInterface revamp (PR #165441)

[Amr Hesham via cfe-commits]

AmrDeveloper wrote:

I will merge to fix building ClangIR and if there is a review comment to improve something, i will address it as follow up

https://github.com/llvm/llvm-project/pull/165441