Remove obsolete TODO

The downscaling was implemented in I35377cdb5d61ee6e23fccc2bffb5d3aec6ca2b7d so this comment is obsolete now.

Bug: 228941516
Test: n/a
Change-Id: I5e72cb3aec253796854274725f64a7c86bd7c380

core/java/android/app/Notification.java

@@ -7944,8 +7944,6 @@ public class Notification implements Parcelable
          * @hide
          */
         public MessagingStyle setShortcutIcon(@Nullable Icon conversationIcon) {
-            // TODO(b/228941516): This icon should be downscaled to avoid using too much memory,
-            // see reduceImageSizes.
             mShortcutIcon = conversationIcon;
             return this;
         }