Make workspace users clean up
Steps to reproduce
Services using the workspace should not just leave all artifacts in there, hoping that a successful cleanup operation will remove the trash at the end of a workflow but should remove whatever they create from the workspace, leaving everything that is passed on during the workflow (linked in the media package) in the working file repository only.
Note that the cleanup oüperation is not guaranteed to run. Either because it is not part of a workflow definition, or because the workflow got canceled due to any reason. The cleanup should only be the fallback solution.