[llvm] [LLVM][MemCpyOpt] Unify alias tags if we optimize allocas (PR #129537)

[Gabriel Baraldi via llvm-commits]

gbaraldi wrote:

Maybe https://godbolt.org/z/qv1Mqo7eP is an interesting test. It comes from a real miscompilation in julia and has alias scopes, no alias and tbaa 

https://github.com/llvm/llvm-project/pull/129537