Temporairly revert "[CGCall] Annotate `this` argument with alignment"

As per @jyknight, "It seems like there's a bug with vtable thunks getting the wrong information."
See https://reviews.llvm.org/D99790#2680857, https://godbolt.org/z/MxhYMe1q7

This reverts commit 0aa0458f1429372038ca6a4edc7e94c96cd9a753.

GitOrigin-RevId: 6270b3a1eafaba4279e021418c5a2c5a35abc002
8 files changed