Bump build time and remove parallel builds (they don't work)

vertical-pod-autoscaler/cloudbuild.yaml

 # See https://cloud.google.com/cloud-build/docs/build-config
-timeout: 3600s
+timeout: 7200s
 # this prevents errors if you don't use both _GIT_TAG and _PULL_BASE_REF,
 # or any new substitutions added in the future.
 options:
@@ -19,7 +19,6 @@ steps:
       - TAG=$_GIT_TAG
     args:
       - release
-    waitFor: ['-']  # The '-' indicates that this step begins immediately.
   - name: "gcr.io/k8s-staging-test-infra/gcb-docker-gcloud:latest"
     dir: pkg/updater
     entrypoint: make
@@ -27,6 +26,5 @@ steps:
       - TAG=$_GIT_TAG
     args:
       - release
-    waitFor: ['-']  # The '-' indicates that this step begins immediately.
 substitutions:
   _GIT_TAG: "0.0.0" # default value, this is substituted at build time