[predicates] fix paginated_rset when the class has no page_size_property Fixes test failure introduced by 70733b2dfd2a, which assumed paginated_rset would only be called on a class with a page_size_property attribute.

[repository] drop usage of no more necessary eschema_eid function since the previous cset, we are guaranteed that repository's entity schema will have their eid attribute properly set, so we don't have anymore to check everytime if some entity schema's .eid attributes is set or not (and retrieve it if not). Related to #10450092