Restyle notification close control (#30262)

Follow-up of https://github.com/zed-industries/zed/pull/30015

Merges suppress and close buttons into one, with `shift` changing the
state and showing different tooltips.
Currently, there's no tooltip for notification suppress action, hence
none is displayed in the video:


https://github.com/user-attachments/assets/678c4d76-a86e-4fe9-8d7b-92996470a8a8

Release Notes:

- N/A

crates/auto_update_ui/src/auto_update_ui.rs

@@ -155,6 +155,7 @@ pub fn notify_if_app_was_updated(cx: &mut App) {
                                 }
                                 cx.emit(DismissEvent);
                             })
+                            .show_suppress_button(false)
                         })
                     },
                 );