feat: use registryMirror addon as Containerd mirror

[dkoshkin]

What problem does this PR solve?:
Depends on #1116

Automatically sets the registryMirror as a Containerd mirror. We're not updating the Cluster object because this should not be a user controller configuration and the IP used as the mirror is determined based on the addon handler and the Service CIDRs.

Tested in a Docker cluster:

$ kubectl port-forward \
  --address=0.0.0.0 \
  --namespace registry-mirror-system \
  pod/registry-mirror-docker-registry-0 5000:5000
# Push an image tag that doesn't exist in dockerhub  
$ crane copy nginx:latest 0.0.0.0:5000/library/nginx:dkoshkin --insecure
$ kubectl run nginx-working --image=docker.io/library/nginx:dkoshkin
$ kubectl run nginx-should-be-broken --image=docker.io/library/nginx:dne
$ kubectl get pods 
NAME                                                              READY   STATUS              RESTARTS   AGE
cluster-autoscaler-0196931c-cb53-7abf-aa89-49c82c42ced5-86w5j8c   0/1     ContainerCreating   0          19m
nginx-should-be-broken                                            0/1     ErrImagePull        0          11m
nginx-working                                                     1/1     Running             0          11m

Which issue(s) this PR fixes:
Fixes #

How Has This Been Tested?:

Special notes for your reviewer:

[github-actions]

This PR/issue depends on:

• feat: add registry addon #1116
  By Dependent Issues (🤖). Happy coding!