Don't initialize things twice

src/Avalonia.ReactiveUI/AppBuilderExtensions.cs

@@ -18,7 +18,6 @@ namespace Avalonia.ReactiveUI
             return builder.AfterPlatformServicesSetup(_ =>
             {
                 PlatformRegistrationManager.SetRegistrationNamespaces(RegistrationNamespace.Avalonia);
-                Locator.CurrentMutable.InitializeReactiveUI();
                 RxApp.MainThreadScheduler = AvaloniaScheduler.Instance;
                 Locator.CurrentMutable.RegisterConstant(new AvaloniaActivationForViewFetcher(), typeof(IActivationForViewFetcher));
                 Locator.CurrentMutable.RegisterConstant(new AutoDataTemplateBindingHook(), typeof(IPropertyBindingHook));