Update k8s registry references

## Describe the feature <!-- Please also discuss possible business value --> Per https://github.com/kubernetes/k8s.io/issues/4780, Kubernetes is migrating its image registry to registry.k8s.io, and this repository is impacted. We have to update the references of k8s.gcr.io to registry.k8s.io by April 3rd to remain up-to-date. Here's a quick search for k8s.gcr.io on this repo. [[search result]](https://github.com/search?q=org%3Adapr%20%22k8s.gcr.io%22&type=code). Note that there may be other valid references (like, in the form of generated code, etc) which we have to be aware of. ## Release Note <!-- How should this new feature be announced in our release notes? It can be populated later. --> <!-- Keep it as a single line. Examples: --> <!-- RELEASE NOTE: **ADD** New feature in Dapr. --> <!-- RELEASE NOTE: **FIX** Bug in runtime. --> <!-- RELEASE NOTE: **UPDATE** Runtime dependency. --> RELEASE NOTE: - Update k8s registry from k8s.gcr.io to registry.k8s.io