[web/autoform] fix regression introduced by #5758ba784ebd The changes from cset 5758ba784ebd "[autoform] when building inlined-form view for a relation, consider related entities intead of other views" lead to an unexpected 'add new' link on creation of an entity with inlined form for a relation of cardinality 1. To avoid this, we should consider formviews and not existing relations when the entity is being created. Closes #10860258

raise NotImplementedError("Cannot migrate such an old version. Use intermediate Cubiweb version (try 3.16.x)")