Revert change from kill to System.Environment.Exit

Author: jamescrosswell

integration-test/net9-maui/App.xaml.cs

@@ -104,7 +104,7 @@ public static void Kill()
 #if ANDROID
         // prevent auto-restart
         Platform.CurrentActivity?.FinishAffinity();
-        System.Environment.Exit(0);
+        Process.KillProcess(Process.MyPid());
 #elif IOS
         System.Environment.Exit(0);
 #endif