Preparing Google Cloud deployments for Docker Hub pull request limits

As Docker announced here: https://www.docker.com/blog/scaling-docker-to-serve-millions...

Docker is planning to make changes to the Docker Hub container registry that will cause a lot of pain and potentially some outages for folks implicitly relying on Docker Hub. Google's report states images could appear and disappear from Google's cache of Docker Hub at any moment, and a cache miss could result in containers failing to start.

The resolution steps are frustrating as well. Every Kubernetes pod that depends on a public image needs a `imagePullSecrets` setting, and every Kubernetes namespace needs a Docker pull secret.

My opinions on this change notwithstanding, I think the timeline for this change was too short for the magnitude of the impact.