simplify animated_material example (bevyengine#11576)

# Objective

- example `animated_material` is more complex that needed to show how to
animate materials
- it makes CI crash because it uses too much memory

## Solution

- Simplify the example

examples/3d/animated_material.rs

@@ -1,17 +1,21 @@
 //! Shows how to animate material properties
 
 use bevy::prelude::*;
-use bevy::utils::HashSet;
 
 fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
         .add_systems(Startup, setup)
-        .add_systems(Update, (animate_materials, make_materials_unique))
+        .add_systems(Update, animate_materials)
         .run();
 }
 
-fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
+fn setup(
+    mut commands: Commands,
+    asset_server: Res<AssetServer>,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<StandardMaterial>>,
+) {
     commands.spawn((
         Camera3dBundle {
             transform: Transform::from_xyz(3.0, 1.0, 3.0)
@@ -25,11 +29,12 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
         },
     ));
 
-    let helmet = asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0");
-    for x in -2..3 {
-        for z in -2..3 {
-            commands.spawn(SceneBundle {
-                scene: helmet.clone(),
+    let cube = meshes.add(shape::Cube { size: 0.5 });
+    for x in -1..2 {
+        for z in -1..2 {
+            commands.spawn(PbrBundle {
+                mesh: cube.clone(),
+                material: materials.add(Color::WHITE),
                 transform: Transform::from_translation(Vec3::new(x as f32, 0.0, z as f32)),
                 ..default()
             });
@@ -50,29 +55,6 @@ fn animate_materials(
                 0.5,
             );
             material.base_color = color;
-            material.emissive = color;
-        }
-    }
-}
-
-/// This is needed because by default assets are loaded with shared materials
-/// But we want to animate every helmet independently of the others, so we must duplicate the materials
-fn make_materials_unique(
-    mut material_handles: Query<&mut Handle<StandardMaterial>>,
-    mut materials: ResMut<Assets<StandardMaterial>>,
-    mut ran: Local<bool>,
-) {
-    if *ran {
-        return;
-    }
-    let mut set = HashSet::new();
-    for mut material_handle in material_handles.iter_mut() {
-        if set.contains(&material_handle.id()) {
-            let material = materials.get(&*material_handle).unwrap().clone();
-            *material_handle = materials.add(material);
-        } else {
-            set.insert(material_handle.id());
         }
-        *ran = true;
     }
 }