Update k8s.gcr.io to registry.k8s.io

[halim-lee]

There was an announcement in https://kubernetes.io/blog/2023/03/10/image-registry-redirect/ : "older k8s.gcr.io registry will be redirected to registry.k8s.io with the eventual goal of sunsetting k8s.gcr.io"

Need to switch to registry.k8s.io for our test pause image

[leochr]

Thank you. Delivered. Closing.