Move minikube prow image to a K8S.io hosted container registry

[medyagh]

our current prow image is hosted in internal google infra
gcr.io/k8s-minikube/prow-test:v0.0.7

https://github.com/kubernetes/test-infra/blob/5c93386c6cdb2d4c7b78d4295877a4d1f384317c/config/jobs/kubernetes/minikube/minikube.yaml#L27

this could be one of the Easier Use cases that we could move the Images to K8s public hosted Infra, since this image rarely needs to be updated (just updates for CVS and refreshing the base image)

[medyagh]

Per Conversation with Sig Infra we can use this example to push images
https://github.com/kubernetes/test-infra/blob/master/config/jobs/image-pushing/k8s-staging-kubetest2.yaml#L4

[medyagh]

based on talking with @ComradeProgrammer in Triage Party
we have 4 questions

in kubetest example
1- they have a GCP Project listed in the yaml file, what do we put there?
2- they have a Folder in a BUKCET, do we just specify our own folder name and it gets created ?
3- they seem to have a /Folder in a GCR as well, (artifact registry) do we automatically get that folder ?
4- in this example is it pushing image every time someone commits to every branch (except dependabot?) can we make it push on release or if the Dockerfile gets changed? or maybe Periodically (every month) ?
5- can image be pushed there on PRs not on Master Branch ?
6- can image be build by a command on a PR or a label (for example ok-to-build-image)