Only make Review App deployment automatic for frontend changes

What does this MR do?

This makes Review App deployment and smoke end-to-end run against them automatic for frontend-related changes, and manual otherwise.

For non-frontend changes, people should just have to start the review-build-cng job and the job would automatically play the review-deploy job once finished (e.g. https://gitlab.com/gitlab-org/gitlab/-/jobs/477627203), and the review-deploy job would do the same and automatically play the review-qa-smoke and review-performance jobs once finished.

Does this MR meet the acceptance criteria?

Conformity

• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content

Closes #208834 (closed).

.gitlab/ci/dev-fixtures.gitlab-ci.yml

@@ -11,7 +11,7 @@
     SEED_CYCLE_ANALYTICS: "true"
     SEED_PRODUCTIVITY_ANALYTICS: "true"
     CYCLE_ANALYTICS_ISSUE_COUNT: 1
-    SIZE: 0 # number of external projects to fork, requires network connection
+    SIZE: 0  # number of external projects to fork, requires network connection
     # SEED_NESTED_GROUPS: "false" # requires network connection
 
 run-dev-fixtures: