Fix rendering of join permissible zones.

The zones themselves are supposed to be unstroked because we only want
to stroke the boundaries of the zone that are preferred.

client/src/components/waypointdebugzones/JoinZones.tsx

@@ -65,6 +65,7 @@ function JoinZones(props: JoinZonesProps) {
             positions={zone}
             color="#80BA80"
             interactive={false}
+            stroke={false}
           />
         );
       })}