Fix API docs referencing a default that is not defined

This is a left over from an earlier design of this API

Author: robsdedude

src/neo4j/_work/summary.py

@@ -805,8 +805,6 @@ def position(self) -> SummaryInputPosition | None:
         The position of the input that caused the status (if applicable).
 
         This is vendor-specific information.
-        If not provided, it defaults to :class:`SummaryInputPosition`'s
-        default.
 
         Only notifications (see :attr:`.is_notification`) have a meaningful
         position.