Remove unescessary unimplemented (#32264)

Release Notes:

- N/A

crates/gpui/src/platform/linux/wayland/window.rs

@@ -979,7 +979,6 @@ impl PlatformWindow for WaylandWindow {
     }
 
     fn on_hit_test_window_control(&self, _callback: Box<dyn FnMut() -> Option<WindowControlArea>>) {
-        unimplemented!()
     }
 
     fn on_appearance_changed(&self, callback: Box<dyn FnMut()>) {

crates/gpui/src/platform/linux/x11/window.rs

@@ -1409,7 +1409,6 @@ impl PlatformWindow for X11Window {
     }
 
     fn on_hit_test_window_control(&self, _callback: Box<dyn FnMut() -> Option<WindowControlArea>>) {
-        unimplemented!()
     }
 
     fn on_appearance_changed(&self, callback: Box<dyn FnMut()>) {

crates/gpui/src/platform/mac/window.rs

@@ -1147,7 +1147,6 @@ impl PlatformWindow for MacWindow {
     }
 
     fn on_hit_test_window_control(&self, _callback: Box<dyn FnMut() -> Option<WindowControlArea>>) {
-        unimplemented!()
     }
 
     fn on_appearance_changed(&self, callback: Box<dyn FnMut()>) {