Follow-up from "Ensure child pipeline jobs are created in scheduled child pipelines"

The following discussion from !72477 (merged) should be addressed:

@alberts-gitlab started a discussion:
In a follow up, we might be able to simplify this to something like the following, as the job should be always be created as long as the child pipeline is created by start-review-app-pipeline.
```
.review:rules:review-build-cng:
  rules:
    - <<: *if-dot-com-gitlab-org-merge-request
      changes: *code-patterns
      allow_failure: true
    - <<: *if-dot-com-gitlab-org-merge-request
      changes: *qa-patterns
      allow_failure: true
    - when: always
```
The other review app child pipeline job rules could also be simplified in a similar manner.

For now, we should fix the scheduled pipeline first.