[MemorySSA] Reset location size if IsGuaranteedLoopInvariant after phi tranlation

We set the Location size to beforeOrAfter if the Location value is not
guaranteed loop invariant. But in some cases, we need to reset the
location size if the location size is precise after phi tranlation of
location value. This will improve MemorySSA analysis results.

Differential Revision: https://reviews.llvm.org/D134161