`ConstantRange::binaryXor` gives poor results as it currently depends on
`KnownBits::operator^`.
Since `sub A, B` is canonicalized into `xor A, B` if `B` is the subset
of `A`, this patch reverts the transform in `ConstantRange::binaryXor`,
which will give better results.
Alive2: https://alive2.llvm.org/ce/z/bmTMV9Fixes#79696.
d9e92765c5