ci: Get rid of the `cloud-native-image` job

Signed-off-by: Rémy Coutable <remy@rymai.me>

.gitlab/ci/cng.gitlab-ci.yml

-cloud-native-image-env:
-  extends:
-    - .default-retry
-    - .cng:rules
-  image: ${GITLAB_DEPENDENCY_PROXY}ruby:2.7-alpine3.13
-  stage: post-test
-  before_script:
-    - source ./scripts/utils.sh
-    - install_gitlab_gem
-  script:
-    - 'ruby -r./scripts/trigger-build.rb -e "puts Trigger.variables_for_env_file(Trigger::CNG.new.variables)" > build.env'
-    - cat build.env
-  artifacts:
-    reports:
-      dotenv: build.env
-    paths:
-      - build.env
-    expire_in: 7 days
-    when: always
-
-cloud-native-image:
-  extends: .cng:rules
-  stage: post-test
-  needs: ["cloud-native-image-env"]
-  inherit:
-    variables: false
-  variables:
-    TOP_UPSTREAM_SOURCE_PROJECT: "${TOP_UPSTREAM_SOURCE_PROJECT}"
-    TOP_UPSTREAM_SOURCE_REF: "${TOP_UPSTREAM_SOURCE_REF}"
-    TOP_UPSTREAM_SOURCE_JOB: "${TOP_UPSTREAM_SOURCE_JOB}"
-    TOP_UPSTREAM_SOURCE_SHA: "${TOP_UPSTREAM_SOURCE_SHA}"
-    TOP_UPSTREAM_MERGE_REQUEST_PROJECT_ID: "${TOP_UPSTREAM_MERGE_REQUEST_PROJECT_ID}"
-    TOP_UPSTREAM_MERGE_REQUEST_IID: "${TOP_UPSTREAM_MERGE_REQUEST_IID}"
-    GITLAB_REF_SLUG: "${GITLAB_REF_SLUG}"
-    # CNG pipeline specific variables
-    GITLAB_VERSION: "${GITLAB_VERSION}"
-    GITLAB_TAG: "${GITLAB_TAG}"
-    GITLAB_ASSETS_TAG: "${GITLAB_ASSETS_TAG}"
-    FORCE_RAILS_IMAGE_BUILDS: "${FORCE_RAILS_IMAGE_BUILDS}"
-    CE_PIPELINE: "${CE_PIPELINE}"  # Based on https://docs.gitlab.com/ee/ci/jobs/job_control.html#check-if-a-variable-exists, `if: '$CE_PIPELINE'` will evaluate to `false` when this variable is empty
-    EE_PIPELINE: "${EE_PIPELINE}"  # Based on https://docs.gitlab.com/ee/ci/jobs/job_control.html#check-if-a-variable-exists, `if: '$EE_PIPELINE'` will evaluate to `false` when this variable is empty
-    GITLAB_SHELL_VERSION: "${GITLAB_SHELL_VERSION}"
-    GITLAB_ELASTICSEARCH_INDEXER_VERSION: "${GITLAB_ELASTICSEARCH_INDEXER_VERSION}"
-    GITLAB_KAS_VERSION: "${GITLAB_KAS_VERSION}"
-    GITLAB_WORKHORSE_VERSION: "${GITLAB_WORKHORSE_VERSION}"
-    GITLAB_PAGES_VERSION: "${GITLAB_PAGES_VERSION}"
-    GITALY_SERVER_VERSION: "${GITALY_SERVER_VERSION}"
-  trigger:
-    project: gitlab-org/build/CNG
-    branch: $TRIGGER_BRANCH
-    strategy: depend

.gitlab/ci/rules.gitlab-ci.yml

@@ -620,15 +620,6 @@
     - changes: *ci-build-images-patterns
     - changes: *code-qa-patterns
 
-#############
-# CNG rules #
-#############
-.cng:rules:
-  rules:
-    - <<: *if-dot-com-gitlab-org-and-security-tag
-      when: manual
-      allow_failure: true
-
 ######################
 # CI Templates Rules #
 ######################

doc/development/testing_guide/review_apps.md

@@ -172,8 +172,6 @@ subgraph "CNG-mirror pipeline"
      them in its [registry](https://gitlab.com/gitlab-org/build/CNG-mirror/container_registry).
    - We use the [`CNG-mirror`](https://gitlab.com/gitlab-org/build/CNG-mirror) project so that the `CNG`, (Cloud
      Native GitLab), project's registry is not overloaded with a lot of transient Docker images.
-   - Note that the official CNG images are built by the `cloud-native-image`
-     job, which runs only for tags, and triggers itself a [`CNG`](https://gitlab.com/gitlab-org/build/CNG) pipeline.
 1. Once `review-build-cng` is done, the [`review-deploy`](https://gitlab.com/gitlab-org/gitlab/-/jobs/467724810) job
    deploys the Review App using [the official GitLab Helm chart](https://gitlab.com/gitlab-org/charts/gitlab/) to
    the [`review-apps`](https://console.cloud.google.com/kubernetes/clusters/details/us-central1-b/review-apps?project=gitlab-review-apps)