Canary jobs need to use the staging repo

[msau42]

We now have prod images in k8s.gcr.io/sig-storage, but canary images are in gcr.io/k8s-staging-sig-storage

https://storage.googleapis.com/kubernetes-jenkins/logs/ci-kubernetes-csi-canary-on-kubernetes-1-17/1309518998437629952/build-log.txt

  Warning  Failed     5m38s (x2 over 5m50s)  kubelet            Failed to pull image "k8s.gcr.io/sig-storage/csi-node-driver-registrar:canary": rpc error: code = NotFound desc = failed to pull and unpack image "k8s.gcr.io/sig-storage/csi-node-driver-registrar:canary": failed to resolve reference "k8s.gcr.io/sig-storage/csi-node-driver-registrar:canary": k8s.gcr.io/sig-storage/csi-node-driver-registrar:canary: not found

[msau42]

/assign

Testing in kubernetes-csi/csi-driver-host-path#202