Quarantine instancetype tests

Test fails with logs in the velero pods as:
`failed to list instancetype.kubevirt.io/v1beta1,
Resource=virtualmachineinstancetype: the server could not find the
requested resource`
Until we figure out why I'll quarantine the tests so the others
can pass.

Signed-off-by: Shelly Kagan <skagan@redhat.com>

tests/vm_backup_test.go

@@ -200,7 +200,7 @@ var _ = Describe("[smoke] VM Backup", func() {
 	})
 
 	Context("VM and VMI object graph backup", func() {
-		Context("with instancetypes and preferences", func() {
+		PContext("with instancetypes and preferences", func() {
 			nsDelFunc := func() {
 				err := f.KvClient.VirtualMachineInstancetype(f.Namespace.Name).
 					Delete(context.Background(), instancetypeName, metav1.DeleteOptions{})