Fix test migration crash waiting to happen due to inferred relations
Avoid crashing when a relation definition which is already known (due to
being inferred) gets explicitly added. As explained in a comment, this
would deserve more thinking, but at least this fixes a test failure with
computed relations.
drop_relation_definition('CWSourceSchemaConfig', 'cw_schema', 'CWAttribute')
sync_schema_props_perms('cw_schema')