Reduce the widget cell horizontal padding

With new grid, David suggested reducing padding on widget cell to be
able to show side by side widgets as before. Widget sizes are slightly
larger in new grid.

Bug: N/A
Test: Screenshot tests
Flag: EXEMPT bugfix
Change-Id: I3b3b55930b9e4ad9064151ccfe77ba27d8289860
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 212534b..c48f140 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -191,7 +191,7 @@
 
     <!-- Widget tray -->
     <dimen name="widget_cell_vertical_padding">8dp</dimen>
-    <dimen name="widget_cell_horizontal_padding">8dp</dimen>
+    <dimen name="widget_cell_horizontal_padding">4dp</dimen>
     <dimen name="widget_cell_title_font_size">14sp</dimen>
     <integer name="widget_cell_title_font_weight">500</integer>
     <dimen name="widget_cell_title_line_height">20sp</dimen>