Add stage ids and wait for image build

cloudbuild.yaml

@@ -1,15 +1,19 @@
 # See https://cloud.google.com/cloud-build/docs/build-config
 steps:
-  - name: gcr.io/cloud-builders/docker
+  - id: build-image
+    name: gcr.io/cloud-builders/docker
     entrypoint: "/usr/bin/make"
     args:
       - "push-images"
       - "TAG=$_GIT_TAG"
-  - name: "gcr.io/google.com/cloudsdktool/cloud-sdk"
+  - id: deploy-staging
+    name: "gcr.io/google.com/cloudsdktool/cloud-sdk"
     entrypoint: "/usr/bin/make"
     args:
       - "deploy"
       - "TAG=$_GIT_TAG"
+    waitFor:
+      - build-image
 substitutions:
   # variables set by kubernetes/test-infra/images/builder
   # set by image-builder to vYYYYMMDD-hash