Reduce padding around text in chooser grid.

After switching to a 5-column layout, a lot of app names (e.g.
"Facebook") were truncated. This allows the text to be a bit wider than
the image to prevent us from truncating too much.

Bug: 269755947
Test: Visual verification and looking at hierarchy viewer.
Change-Id: Idf1c3e42ea926b9253db47741244a3ca149e936e
1 file changed