Remove edge effect type from the API.

Fixes: 186758538

Relnote: "Removes edge effect type from the API -- EdgeEffect now
supports only stretch edge effect for all applications."

Test: existing tests, modified to work with stretch
Change-Id: Iec7a9d4a0316ff3ba7297c4565bb881a1adcf949

tests/HwAccelerationTest/res/layout/stretch_layout.xml

@@ -16,7 +16,6 @@
 <ScrollView
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/scroll_view"
-    android:edgeEffectType="stretch"
     android:layout_width="match_parent"
     android:layout_height="match_parent" >
     <LinearLayout
@@ -26,7 +25,6 @@
 
         <HorizontalScrollView
             android:id="@+id/horizontal_scroll_view"
-            android:edgeEffectType="stretch"
             android:layout_width="match_parent"
             android:layout_height="match_parent">
             <LinearLayout