Implement a GitLab CI pipeline with dynamic child pipelines generated from changed paths using rules and the artifact strategy

Steps

1. Write a parent pipeline YAML with a generate stage job that runs a script to inspect changed files and emit a child pipeline YAML file as an artifact, using git diff or similar to identify affected components
2. Define a trigger job in the parent pipeline that references the generated artifact using the trigger:include:artifact syntax and sets strategy: depend to make the parent wait for child completion
3. In the generator script, produce a valid GitLab CI YAML file with stages and jobs for only the affected components, keeping unused jobs out of the child pipeline to reduce execution time
4. Add rules conditions to the parent generate job so it runs only on merge request or push events and not on scheduled pipelines where full builds are expected
5. Validate the child pipeline output by logging the generated YAML and comparing it against expected jobs for a known set of changed paths