Higher-level processes should not have a workflow

[matthias-ronge]

Currently, higher-level processes get the same workflow as their children, and tasks, and the tasks are open for operator processing, as is usual at the beginning of workflow.

Goal: There is nothing to do with higher-level processes. They should be hidden (like completed processes) and have no tasks, especially no open tasks. Solution is subject to discussion, no production template seems the most logical. But can also be a dummy workflow without steps, or whatever.

[matthias-ronge]

Twinned with issue #3190