fix andriod update button cannot be clicked (#10394)

1. Remove `canLaunchUrl`, which fix the issue
2. Remove `unregisterEventHandler` of `kCheckSoftwareUpdateFinish` when
   connection page dispose, it's registered on main.

Signed-off-by: 21pages <sunboeasy@gmail.com>

flutter/lib/desktop/pages/desktop_home_page.dart

@@ -834,10 +834,6 @@ class _DesktopHomePageState extends State<DesktopHomePage>
     _uniLinksSubscription?.cancel();
     Get.delete<RxBool>(tag: 'stop-service');
     _updateTimer?.cancel();
-    if (!bind.isCustomClient()) {
-      platformFFI.unregisterEventHandler(
-          kCheckSoftwareUpdateFinish, kCheckSoftwareUpdateFinish);
-    }
     WidgetsBinding.instance.removeObserver(this);
     super.dispose();
   }