chore: removed unecessary end callback (#30)

lib/game/components/score_points.dart

@@ -22,9 +22,4 @@ class BallScorePointsCallback extends ContactCallback<Ball, ScorePoints> {
   ) {
     ball.gameRef.read<GameBloc>().add(Scored(points: scorePoints.points));
   }
-
-  // TODO(alestiago): remove once this issue is closed.
-  // https://github.com/flame-engine/flame/issues/1414
-  @override
-  void end(Ball _, ScorePoints __, Contact ___) {}
 }

lib/game/components/wall.dart

@@ -63,7 +63,4 @@ class BottomWallBallContactCallback extends ContactCallback<Ball, BottomWall> {
   void begin(Ball ball, BottomWall wall, Contact contact) {
     ball.lost();
   }
-
-  @override
-  void end(_, __, ___) {}
 }