refactor: update dash nest games

packages/pinball_components/sandbox/lib/stories/flutter_forest/big_dash_nest_bumper_game.dart

@@ -16,7 +16,7 @@ class BigDashNestBumperGame extends BasicBallGame with Traceable {
   Future<void> onLoad() async {
     await super.onLoad();
     camera.followVector2(Vector2.zero());
-    await add(BigDashNestBumper()..priority = 1);
+    await add(DashNestBumper.main()..priority = 1);
     await traceAllBodies();
     await traceAllBodies();
   }

packages/pinball_components/sandbox/lib/stories/flutter_forest/small_dash_nest_bumper_a_game.dart

@@ -16,7 +16,7 @@ class SmallDashNestBumperAGame extends BasicBallGame with Traceable {
   Future<void> onLoad() async {
     await super.onLoad();
     camera.followVector2(Vector2.zero());
-    await add(SmallDashNestBumper.a()..priority = 1);
+    await add(DashNestBumper.a()..priority = 1);
     await traceAllBodies();
     await traceAllBodies();
   }

packages/pinball_components/sandbox/lib/stories/flutter_forest/small_dash_nest_bumper_b_game.dart

@@ -16,7 +16,7 @@ class SmallDashNestBumperBGame extends BasicBallGame with Traceable {
   Future<void> onLoad() async {
     await super.onLoad();
     camera.followVector2(Vector2.zero());
-    await add(SmallDashNestBumper.b()..priority = 1);
+    await add(DashNestBumper.b()..priority = 1);
     await traceAllBodies();
     await traceAllBodies();
   }