ui2: Do not enable 'stories' feature by default.

This cuts down LLVM IR size from 3 million lines to 700k in debug build.
This then leads to ~3s compile time in debug build (without incremental on ui itself), as opposed to 10.5s on main.

crates/ui2/src/components/button.rs

@@ -1,6 +1,6 @@
 use std::sync::Arc;
 
-use gpui::{div, DefiniteLength, Hsla, MouseButton, StatefulInteractiveComponent, WindowContext};
+use gpui::{DefiniteLength, Hsla, MouseButton, StatefulInteractiveComponent, WindowContext};
 
 use crate::prelude::*;
 use crate::{h_stack, Icon, IconButton, IconElement, Label, LineHeightStyle, TextColor};