Allow resources to be marked for deletion without waiting

[adriansuarez]

What would you like to be added:

I would like to be able to issue an asynchronous deletion request without waiting for the resources to be deleted. Currently there is a hardwired polling for resources appearing in the delete property of TestStep. Unless I am missing something in the documentation, it does not look like there is any way to prevent the test framework from waiting for the resources to go away.

Why is this needed:

I'd like to be able to verify that finalizers are handled correctly by my controller, e.g. by marking a resource for deletion that is blocked by the existence of some other resource, verifying that it does not get deleted, and then unblocking it by deleting the other resource.