Fix text sizes and alignment in drop target

Drop target button texts are being resized incorrectly.
When both buttons are visible, the text is considerably smaller compared
to only one visible button. This happens even for the default display and font scale 1.

Fix: 271279172
Test: manual. test all combinations of display size and font size.
Test: HomeScreenEditStateImageTest
Change-Id: Ib001dcf8b096c65b138946bdad49cf8199fb5b1d