[AArch64] Don't use tbl lowering if ZExt can be folded into user.

If the ZExt can be lowered to a single ZExt to the next power-of-2 and
the remaining ZExt folded into the user, don't use tbl lowering.

Fixes #62620.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D150482