Add trackNum to UnsupportedAppUsage annotation of createFromFamiliesWithDefault

We won't change anything of the reflection access of creatFromFamiliesWithDefault.
So we only add the bug number for tracking purpose.
And the TODO is removed because the corresponding ticket is marked as fix.

Bug: 123768395
Test: atest TypefaceTest
Change-Id: I802392859fb611ea558d0c06fc0bd77f5a38c439

graphics/java/android/graphics/Typeface.java

@@ -1019,9 +1019,8 @@ public class Typeface {
 
     /**
      * This method is used by supportlib-v27.
-     * TODO: Remove private API use in supportlib: http://b/72665240
      */
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(trackingBug = 123768395)
     private static Typeface createFromFamiliesWithDefault(
             android.graphics.FontFamily[] families, int weight, int italic) {
         return createFromFamiliesWithDefault(families, DEFAULT_FAMILY, weight, italic);