cleanup workspace after a job, so that we don't run out of disk
cleanup workspace after a job, so that we don't run out of disk

Jenkins has a nice publisher hook for that, that works always
no matter whether the job succeeded or failed, and it always
does it after the job completed, which means we're saving
disk space for the concurrent trackupstream runs.

aspiers/automation,gosipyan/automation,aspiers/automation,aspiers/automation,gosipyan/automation,gosipyan/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,gosipyan/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,aspiers/automation