Make Maestro++ know about the opt-in option of publishing using pipelines

[JohnTortugo]

The publishing using pipelines mechanism for opt-in is based on build definition variables, that works fine for the builds. However, Maestro++ doesn't have access to that information (variable) and will try to run pipelines associated with channels for every build that finishes - independently of the repo from the build having opted in publishing using pipelines or not.