misc: chore: Use string.Empty in more places where it's snuck back

src/Ryujinx/UI/Views/Settings/SettingsNetworkView.axaml.cs

@@ -7,23 +7,26 @@ namespace Ryujinx.Ava.UI.Views.Settings
 {
     public partial class SettingsNetworkView : UserControl
     {
+        private readonly Random _random;
+        
         public SettingsViewModel ViewModel;
 
         public SettingsNetworkView()
         {
+            _random = new Random();
             InitializeComponent();
         }
 
         private void GenLdnPassButton_OnClick(object sender, RoutedEventArgs e)
         {
             byte[] code = new byte[4];
-            new Random().NextBytes(code);
+            _random.NextBytes(code);
             ViewModel.LdnPassphrase = $"Ryujinx-{BitConverter.ToUInt32(code):x8}";
         }
 
         private void ClearLdnPassButton_OnClick(object sender, RoutedEventArgs e)
         {
-            ViewModel.LdnPassphrase = "";
+            ViewModel.LdnPassphrase = string.Empty;
         }
     }
 }