[X86] Update avx512vbmi2 intrinsic tests to avoid adds

As noticed in D119654, by adding the masked intrinsics results together
we can end up with the selects being canonicalized away from the
intrinsic - this isn't what we want to test here so replace with a
insertvalue chain into a aggregate instead to retain all the results.

Differential Revision: https://reviews.llvm.org/D121196