Consider new pipeline rule syntax

Rule formats are changing with https://gitlab.com/gitlab-org/gitlab-ee/issues/27863 in 12.3. We should consider piloting these in an iterative fashion (similar to DAG) in the GitLab pipeline

That should also fix gitlab-com/gl-infra/delivery#542 (closed).

Plan

We'll implement the rules keyword incrementally where this makes the most sense first, and also to get to learn this new feature first.

1. Merge package-and-qa and package-and-qa-manual into a single package-and-qa job using rules: !21945 (merged)
2. Merge schedule:package-and-qa and package-and-qa into a single package-and-qa job using rules: !22357 (merged)
3. Use rules for the qa-frontend-node:* jobs (and make them run on master only) and the webpack-dev-server job: !22538 (merged)
4. Use rules for the gitlab:assets:compile * and compile-assets * jobs: !23351 (merged)
5. Use rules for .gitlab/ci/frontend.gitlab-ci.yml: !24061 (merged)
6. Use rules for .gitlab/ci/cache-repo.gitlab-ci.yml: !24306 (merged)
7. Use rules for .gitlab/ci/cng.gitlab-ci.yml: !24308 (merged)
8. Use rules for .gitlab/ci/docs.gitlab-ci.yml: !24353 (merged)
9. Use rules for .gitlab/ci/memory.gitlab-ci.yml: !24458 (merged)
10. Use rules for .gitlab/ci/pages.gitlab-ci.yml: !24459 (merged)
11. Use rules for .gitlab/ci/qa.gitlab-ci.yml: !24488 (merged)
12. Use rules for .gitlab/ci/rails.gitlab-ci.yml: !24492 (merged)
13. Use rules for .gitlab/ci/dev-fixtures.gitlab-ci.yml: !24492 (merged)
14. Use rules for .gitlab/ci/releases.gitlab-ci.yml: !24616 (merged)
15. Use rules for .gitlab/ci/reports.gitlab-ci.yml: !24624 (merged)
16. Use rules for .gitlab/ci/review.gitlab-ci.yml: !24803 (merged)
17. Use rules for .gitlab/ci/setup.gitlab-ci.yml: !24804 (merged)
18. Use rules for .gitlab/ci/test-metadata.gitlab-ci.yml: !24805 (merged)
19. Remove duplication of YAML anchors by moving rules hidden jobs into shared CI config file (#202585 (closed)): !25150 (merged)
20. Actually make most jobs always run on master - #206971 (closed)
21. Use rules to make jobs that are only run in schedules, when: manual for MR pipelines - #206978 (closed)
22. Implement dast for schedule master: https://gitlab.com/gitlab-org/gitlab/issues/31160