Use chain in breakout example (bevyengine#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),
- move_paddle
- .before(check_for_collisions)
- .after(apply_velocity),
- play_collision_sound.after(check_for_collisions),
- ),
+ play_collision_sound,
+ )
+ // `chain`ing systems together runs them in order
+ .chain(),
  )
  .add_systems(Update, (update_scoreboard, bevy::window::close_on_esc))
  .run();