Restrict FLAG_SUPPORT_STATIC_TRANSFORMATIONS usage

There is a proper setter for it already called
setStaticTransformationsEnabled. There is not a strong motivation for a
getter as this is only used to instruct the class to invoke
getChildStaticTransformation when a child is drawn. And any class
setting this flag to true is supposed to override that getter. Also I
was not able to find any reasonable public usages of the flag.

Bug: b/123769647
Test: N/A
Change-Id: I14ea7d560a5318cc372ac84dc5a1daad626e4f7e

core/java/android/view/ViewGroup.java

@@ -314,7 +314,7 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
      *
      * {@hide}
      */
-    @UnsupportedAppUsage
+    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 123769647)
     protected static final int FLAG_SUPPORT_STATIC_TRANSFORMATIONS = 0x800;
 
     // UNUSED FLAG VALUE: 0x1000;