ray: [k8s] min_workers doesn't seem to be honored

What is the problem? & Reproduction (REQUIRED)

Ray version 1.2, k8s 18.6 and 19.x, Ubuntu 18.04

i’ve been playing around with various min_worker settings and have been seeing inconsistent behavior, e.g when i set min_worker to 10, the system indeed ended up with 10 pods, but when i changed it to 30, I only ended up with one or no worker. The cluster yaml i used as a starting point is just this one: https://github.com/ray-project/ray/blob/6af02913470fa9f394e0fe37b8a7115e10a29a2b/python/ray/autoscaler/kubernetes/example-full.yaml#L98 .

To reproduce this, i think it should be sufficient to setup a larger k8s cluster and run ray up with the modified cluster yaml i described above. see this thread for further background information: https://discuss.ray.io/t/min-workers-doesnt-seem-to-be-honored/1002

@richardliaw ^^