Updating widget tray theme

Using standard theme attributes rather than custom color codes, so
that it plays nice with system theme changes.

Bug: 34819119
Bug: 34897402
Bug: 21446746
Change-Id: I265fba3ceae8873650fd09e4704838d313155e83
diff --git a/res/layout/all_apps.xml b/res/layout/all_apps.xml
index 1909f3b..5f5b38b 100644
--- a/res/layout/all_apps.xml
+++ b/res/layout/all_apps.xml
@@ -55,7 +55,7 @@
             android:focusable="true"
             android:paddingStart="@dimen/container_fastscroll_thumb_max_width"
             android:paddingEnd="@dimen/container_fastscroll_thumb_max_width"
-            android:theme="@style/CustomOverscroll.Light" />
+            android:theme="@style/AllAppsOverscroll" />
 
         <!-- Fast scroller popup -->
         <TextView