Clean up spicedb orphans

[felixevers]

Describe the chore

#896 introduces a delete capability for specific spicedb relations. Although this delete is not transitive and does not clear orphan's in spicedb relation set.

Keep in mind that this approach will leave leaks (e.g., when deleting an org, all relations to its users and wards will be deleted, but not the relations between a room and such a ward) We believe that's ok for now.
--- #896

Two options to deal with this issue:

1. schedule clean up scripts to check for orphan objects in database.
2. (preferred) build up transitive delete chains (prune connected objects)