Migrating hierarchical processes uses wrong template

[matthias-ronge]

The migration function for creating hierarchical processes uses a child’s production template and the parent process gets the child’s workflow. It has meanwhile been decided that this is wrong, instead parent processes should get an own workflow with one step. The function crashes if no workflow has been created for the migrated child, which is definitely wrong.

Goal: The application must show which hierarchical processes use which ruleset and a possibility to offer for each the assignment of a production template with one step by the operator.

[matthias-ronge]

Cf. #3307

[matthias-ronge]

May have been solved with the introduction of noWorkflow, needs re-testing if it migration already respects noWorkflow yet or not.