Remove dead states code from bevy_ecs (#19210)

`bevy_ecs` was meant to have the `States` and `SubStates`
`proc_macro_derive`s removed when the separate `bevy_state` [was
created](#13216) but they were
missed.

Author: mgi388

crates/bevy_ecs/macros/src/lib.rs

@@ -6,7 +6,6 @@ extern crate proc_macro;
 mod component;
 mod query_data;
 mod query_filter;
-mod states;
 mod world_query;
 
 use crate::{
@@ -548,16 +547,6 @@ pub fn derive_component(input: TokenStream) -> TokenStream {
     component::derive_component(input)
 }
 
-#[proc_macro_derive(States)]
-pub fn derive_states(input: TokenStream) -> TokenStream {
-    states::derive_states(input)
-}
-
-#[proc_macro_derive(SubStates, attributes(source))]
-pub fn derive_substates(input: TokenStream) -> TokenStream {
-    states::derive_substates(input)
-}
-
 #[proc_macro_derive(FromWorld, attributes(from_world))]
 pub fn derive_from_world(input: TokenStream) -> TokenStream {
     let bevy_ecs_path = bevy_ecs_path();