Fix sketchy bubble preference button

We were re-using the same "unselected" drawable for buttons with
different heights, which causes one height to override the other,
leading to unexpected drawable overlap and height/text-line mismatch.

Instead, use separate drawable per button.

Fixes: 154087375
Test: toggle between pref buttons in every font size
Change-Id: I5db6e1eb5150a72a0d8038b0840538a0982a5f67