Use chain in breakout example (#10124)

# Objective

- We should encourage of the simpler to reason about chain.

## Solution

- Use it in the breakout example

---

## Changelog

- Switch breakout to use `chain` instead of `before` and `after`

examples/games/breakout.rs

@@ -59,13 +59,13 @@ fn main() {
         .add_systems(
             FixedUpdate,
             (
+                apply_velocity,
+                move_paddle,
                 check_for_collisions,
-                apply_velocity.before(check_for_collisions),
+                play_collision_sound,
-                move_paddle
+            )
-                    .before(check_for_collisions)
+                // `chain`ing systems together runs them in order
-                    .after(apply_velocity),
+                .chain(),
-                play_collision_sound.after(check_for_collisions),
-            ),
         )
         .add_systems(Update, (update_scoreboard, bevy::window::close_on_esc))
         .run();