WIP: Split populate and create pipelines

What does this MR do?

Adds a concept of bootstrap job:

bootstrap:
  stage: bootstrap
  script: generate-my-config-yaml > ci.yml
  reports:
    gitlab_ci_yml: ci.yml

It will extend the current pipeline with ci.yml.

Idea. Done very hacky way :) (spend 30mins so far on it)

What are the relevant issue numbers?

#45828 (moved)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides