[openFATE 322068] Support Docker Chaining of Services

Feature changed by: Adrian Schröter (adrianSuSE) Feature #322068, revision 3 Title: Support Docker Chaining of Services - Buildservice: Implementation + Buildservice: Done Milestone: 2.8 Priority Requester: Important Projectmanager: Important Requested by: Adrian Schröter (adriansuse) Partner organization: openSUSE.org Description: Current LXC implementation of service chaining tends to break often due to LXC changes. It is also quite hacky. Re-implment it using a pre-build docker container. This allows to use it for more OBS administrators and is hopefully longer lasting. -- openSUSE Feature: https://features.opensuse.org/322068