Fix inconsistent icon size in app list.

Some app icons are really small. This is technically a bug in app, but
not handling it well makes settings UI look strange.

So in addition to setting a max size app icon can use, we just set that
as a only supported size (min == max == 36dp)

Change-Id: I4b3a1b83ab67be469ac74e7d4bb382ae855624d0
Fixes: 115788294
Test: visual