[AArch64] Ignore instructions not supported by CPU in AArch64SVESchedPseudoTest

When adding new Pseudos for instructions that are not supported
by the CPU for which the scheduler model is being tested, the test fails
if these pseudos are not covered by the regex's in the scheduling model.

Rather than failing, this test should check that the CPU supports the
original instruction modelled by the pseudo. If not, the pseudo is
not relevant to the scheduling model being tested.

Reviewed By: dmgreen

Differential Revision: https://reviews.llvm.org/D156094