Add func test to verify kube-proxy is up

[hongbin]

Below is Egor comment in the review https://review.openstack.org/#/c/273289/:

I think it's better to add func test for proxy instead of checking variables. This test is tricky to implement, because round-robin nature of services. And we end up with following implementation: create service with nodePort and test each node in cluster for this port.

[Corey O'Brien (coreypobrien)]

Instead of adding a test for the kube-proxy, I think we need to add something to the startup scripts that fails the build if the kube-proxy doesn't come up correctly.