Timebox: 1h for finding an easy solution! Otherwise we might have to invest more time

To reproduce:

1. try to publish any page to confirm all is working and workflow is enabled
2. go to /modules/workflow/config/workflowManager and change implementation class or simply add a property
3. try to publish same page again ==> fails w/ exception attached

Upon adding/editing property, workflow module is restarted which triggers restart of the engine. However something there doesn't deal w/ restart properly.

Chosen solution

Eventually it was decided not to touch the workflow engine during module reloads cause that would lead it into a broken, no longer working state. Instead we log a message about the need for restarting Magnolia to account for workflow configuration changes.