tilt should prefer a local registry over an in-cluster builder

[nicks]

Currently, if a cluster offers BOTH a local registry and an in-cluster builder, Tilt will prefer the in-cluster builder

We should change this to prefer the local registry

This is not urgent. You have to very deliberately set minikube up this way to fall into this case (our example scripts encourage you to use containerd, which does not have this problem - https://github.com/tilt-dev/minikube-local)