Revert "[Clang] Propagate guaranteed alignment for malloc and others"

The above change assumed that malloc (and friends) would always
allocate memory to getNewAlign(), even for allocations which have a
smaller size. This is not actually required by spec (a 1-byte
allocation may validly have 1-byte alignment).

Some real-world malloc implementations do not provide this guarantee,
and thus this optimization is breaking programs.

Fixes #53540

This reverts commit c2297544.

Differential Revision: https://reviews.llvm.org/D118804