Merge branch 'move-cloud-images-job-stage' into 'master'

Move the cloud-native-image trigger job into the test stage

See merge request gitlab-org/gitlab-ce!21819

.gitlab-ci.yml

@@ -327,7 +327,7 @@ review-docs-cleanup:
 cloud-native-image:
   image: ruby:2.4-alpine
   before_script: []
-  stage: build
+  stage: test
   allow_failure: true
   variables:
     GIT_DEPTH: "1"