Cleanup legacy code from bevy_sprite (#15304)

# Objective

- Remove legacy stuff

crates/bevy_sprite/src/sprite.rs

@@ -10,7 +10,6 @@ use crate::TextureSlicer;
 /// This is commonly used as a component within [`SpriteBundle`](crate::bundle::SpriteBundle).
 #[derive(Component, Debug, Default, Clone, Reflect)]
 #[reflect(Component, Default, Debug)]
-#[repr(C)]
 pub struct Sprite {
     /// The sprite's color tint
     pub color: Color,

crates/bevy_sprite/src/texture_atlas.rs

@@ -21,7 +21,6 @@ use bevy_utils::HashMap;
 #[derive(Asset, Reflect, Debug, Clone)]
 #[reflect(Debug)]
 pub struct TextureAtlasLayout {
-    // TODO: add support to Uniforms derive to write dimensions and sprites to the same buffer
     pub size: UVec2,
     /// The specific areas of the atlas where each texture can be found
     pub textures: Vec<URect>,