Revert "Add GCNotifier class."

This reverts commit d42b22d5e8.

src/Avalonia.Base/Utilities/GCNotifier.cs

@@ -1,29 +0,0 @@
-// Copyright (c) The Avalonia Project. All rights reserved.
-// Licensed under the MIT license. See licence.md file in the project root for full license information.
-
-using System;
-
-namespace Avalonia.Utilities
-{
-    public class GCNotifier
-    {
-        public static event EventHandler GarbageCollected;
-
-        static GCNotifier()
-        {
-            new GCNotifier();
-        }
-
-        ~GCNotifier()
-        {
-            if (Environment.HasShutdownStarted || AppDomain.CurrentDomain.IsFinalizingForUnload())
-            {
-                return;
-            }
-
-            new GCNotifier();
-
-            GarbageCollected?.Invoke(null, EventArgs.Empty);
-        }
-    }
-}