[tests] cleanup old tests

Finally manage.py tests runs through

uncloud_vm/tests.py

@@ -79,22 +79,6 @@ class VMTestCase(TestCase):
 #            msg='VMDiskProduct created with disk image whose status is not active.'
 #        )
 
-    def test_vm_disk_product_creation(self):
-        """Ensure that a user can only create a VMDiskProduct for an existing VM"""
-
-        disk_image = VMDiskImageProduct.objects.create(
-            owner=self.user, name='disk_image', is_os_image=True, is_public=True, size_in_gb=10,
-            status='active'
-        )
-
-        with self.assertRaises(ValidationError, msg='User created a VMDiskProduct for non-existing VM'):
-            # Create VMProduct object but don't save it in database
-            vm = VMProduct()
-
-            vm_disk_product = VMDiskProduct.objects.create(
-                owner=self.user, vm=vm, image=disk_image, size_in_gb=10
-            )
-
 # TODO: the logic tested by this test is not implemented yet.
 #    def test_vm_disk_product_creation_for_someone_else(self):
 #        """Ensure that a user can only create a VMDiskProduct for his/her own VM"""