There's no reason to create an additional test object and use confusing
tricks using __new__(), if we already have a test object as the "test"
parameter.

With this, we can convert all test classes to simple functions.

To make sure we kill the VM after running each test case, add
kill_vm=yes and kill_vm_gracefully=no to qemu_cpu.cfg.

Cc: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>