[llvm-mca] Move bad-input.s test to be target specific

... for now.

This is a follow up to #90474 in response to build bot failures.

This test is intended to check a case where invalid assembly is passed
to llvm-mca.

Unfortunately it appears that a cross-toolchain built with
-DTOOLCHAIN_TARGET_TRIPLE does not have an llvm-mca which works out of
the box if the host target is not enabled.

As a quick fix to make the build bots green, move the test into AArch64
and X86 so that there is reasonable coverage for this test; later I hope
mca can be fixed to work out of the box in this configuration.