chore: Fix several style lints (#17488)

It's not comprehensive enough to start linting on `style` group, but
hey, it's a start.

Release Notes:

- N/A

crates/ui/src/components/button/button_like.rs

@@ -284,7 +284,7 @@ impl ButtonStyle {
         elevation: Option<Elevation>,
         cx: &mut WindowContext,
     ) -> ButtonLikeStyles {
-        let filled_background = element_bg_from_elevation(elevation, cx).fade_out(0.82);
+        element_bg_from_elevation(elevation, cx).fade_out(0.82);
 
         match self {
             ButtonStyle::Filled => ButtonLikeStyles {