Limit automatic CI launch to merge requests
In this MR, we port from except/only/when to use the new and more flexible rules mechanism. With this, we will be able to enable merge_request pipelines. The new pipeline are created when a merge request is created. The idea is merge_request pipeline will start automatically, so that the CI pass will have progress by when a reviewer pass buy. For any other branch, the CI job "manifest" will be made manual. That allow a single click to run the pipeline on your private branches. With the rules, we can extend this as much as we want. This will effectively disable post-merge CI, replacing it by manual CI in case we suspect a regression in master.
Edited by Nicolas Dufresne