Fix the integration test. (#444)

The integration test uses a custom build pipeline. The build pipeline
now has extra arguments for the ubuntu image so we must provide them
here.

Author: chingor13

testapps/integration/test.yaml.in

@@ -1,6 +1,6 @@
 steps:
   - name: '${STAGING_BUILDER_IMAGE}'
-    args: ['--php72-image', 'gcr.io/google-appengine/php72:staging', '--php71-image', 'gcr.io/google-appengine/php71:staging', '--php70-image', 'gcr.io/google-appengine/php70:staging', '--php56-image', 'gcr.io/google-appengine/php56:staging']
+    args: ['--php72-image', 'gcr.io/google-appengine/php72:staging', '--php71-image', 'gcr.io/google-appengine/php71:staging', '--php70-image', 'gcr.io/google-appengine/php70:staging', '--php56-image', 'gcr.io/google-appengine/php56:staging', '--ubuntu-php72-image', 'gcr.io/google-appengine/ubuntu-php72:staging', '--ubuntu-php71-image', 'gcr.io/google-appengine/ubuntu-php71:staging', '--ubuntu-php70-image', 'gcr.io/google-appengine/ubuntu-php70:staging', '--ubuntu-php56-image', 'gcr.io/google-appengine/ubuntu-php56:staging']
   - name: 'gcr.io/cloud-builders/docker:latest'
     args: ['build', '-t', '$_OUTPUT_IMAGE', '.']
 images: