Update InCallService#onConnectionEvent comments.

Update comments to indicate the method is unused and to point developers
to the correct method.

Bug: 31056610
Change-Id: I5d1da69914e0fccd3cf3c504b68acbcf0c70c9c4

telecomm/java/android/telecom/InCallService.java

@@ -449,8 +449,8 @@ public abstract class InCallService extends Service {
     }
 
     /**
-     * Called when a {@link Call} has received a connection event issued by the
-     * {@link ConnectionService}.
+     * Unused; to handle connection events issued by a {@link ConnectionService}, implement the
+     * {@link android.telecom.Call.Callback#onConnectionEvent(Call, String, Bundle)} callback.
      * <p>
      * See {@link Connection#sendConnectionEvent(String, Bundle)}.
      *