DM-807 Archive Jenkins artefact

Created by: amues

Modify Jenkinsfile to build EFU in release mode and archive artefact for CentOS 7. The changes also distribute the containers among all of the build nodes and limits the use of the email notification function. This last change was made to prevent Jenkins from sending more than one email per broken build (e.g. if multiple containers fail) – by doing this we lose the details of which build and where the job failed, though.