tests: Add "no-kvm-pit-device" testcase
    
    Add a test case for when the QEMU_CAPS_NO_KVM_PIT capability is set.
    This capability is mutually exclusive to QEMU_CAPS_KVM_PIT_TICK_POLICY
    and results in the same output regardless of whether "discard" or
    "delay" was specified in the guest XML for 'tickpolicy'.
    
    Signed-off-by: Maxim Nestratov <mnestratov@virtuozzo.com>