chore(build): Update cloudbuild.yaml file (#611)

The currently checked-in Google Cloud Build configs have not been maintained and
are no longer used when producing the official Spinnaker releases. Instead, the
build process generates a GCB config on-the-fly and uses that.

To make the process more clear and make it easier for others to reproduce the
builds, commit the GCB config that is auto-generated to the repo. Also, delete
the unused cloudbuild-tagged.yaml.

cloudbuild.yaml

@@ -1,10 +1,16 @@
 steps:
-- name: 'spinnakerrelease/gradle_cache'
+- name: gcr.io/spinnaker-marketplace/gradle_cache
   env: ["GRADLE_USER_HOME=/gradle_cache/.gradle"]
   entrypoint: "bash"
-  args: [ "-c", "./gradlew echo-web:installDist -x test"]
-- name: 'gcr.io/cloud-builders/docker'
-  args: ["build", "-t", "gcr.io/$PROJECT_ID/$REPO_NAME:$COMMIT_SHA", "-t", "gcr.io/$PROJECT_ID/$REPO_NAME:latest", "-f", "Dockerfile.slim", "."]
+  args: ["-c", "./gradlew echo-web:installDist -x test"]
+- name: gcr.io/cloud-builders/docker
+  # Exclude echo from the slim docker builds since the alpine base image
+  # (which is used in the slim builds) is missing a package gRPC needs to
+  # establish pub/sub listeners.
+  args: ["build", "-t", "gcr.io/$PROJECT_ID/$REPO_NAME:$TAG_NAME", "-f", "Dockerfile", "."]
+  env: ["GRADLE_USER_HOME=/gradle_cache/.gradle"]
 images:
-- 'gcr.io/$PROJECT_ID/$REPO_NAME:$COMMIT_SHA'
-- 'gcr.io/$PROJECT_ID/$REPO_NAME:latest'
+- gcr.io/$PROJECT_ID/$REPO_NAME:$TAG_NAME
+timeout: 3600s
+options:
+  machineType: N1_HIGHCPU_8