migrate away from gcr.io/k8s-testimages (#2967)

Author: zetaab

cloudbuild.yaml

@@ -9,7 +9,7 @@ options:
   substitution_option: ALLOW_LOOSE
   machineType: 'N1_HIGHCPU_8'
 steps:
-  - name: gcr.io/k8s-testimages/gcb-docker-gcloud
+  - name: gcr.io/k8s-staging-test-infra/gcb-docker-gcloud
     entrypoint: bash
     env:
     # default cloudbuild has HOME=/builder/home and docker buildx is in /root/.docker/cli-plugins/docker-buildx