Production templates deleted from a project cannot be added again

[matthias-ronge]

We copied and saved a project. It was then assigned to all production templates to which the source project was assigned. These can be deleted. A deleted production template does not appear again in the selection of production templates that can be assigned to the project. This is a persistent problem, even after a logout / login you can no longer assign it here.

Workaround: You can edit the production templates and assign the project there.

Goal: After deleting a production template, it should be added back to the list of production templates that can be added.

[matthias-ronge]

@markusweigelt commented in #4746:

• Empty template selection but existing templates
• After removing template from project and saving new project config, the template selection is empty
• After creating template, template selection dialog in project config contains all available templates now