test gitlab-ci-templates with another project
It's done this way:
- create a cubicweb/cubes/blog-beta based on blog
- trigger it's pipeline from gitlab-ci-templates while transmiting the used branch
- on gitlab-ci-templates have a tests/remote-gitlab-ci.yml that is the equivalent of a common cube ci template
- blog-beta CI is triggered, it includes tests/remote-gitlab-ci.yml from the remote branch which run all classical job
- if there is a problem or a mistake, gitlab-ci-templates tests will fails