Delete bogus cpu-host-passthrough test

Delete bogus cpu-host-passthrough test

We test the same XML for a type='kvm' domain twice, once with
QEMU_CAPS_KVM (expecting success), once without (expecting failure).

The failure case relies on QEMU_CAPS_MACHINE_OPT not being set,
failing in qemuBuildObsoleteAccelArg.

Checking a domain-type error message in a cpu test is strange.
Delete the negative test to allow assuming QEMU_CAPS_MACHINE_OPT by
default.

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>