Fix Title padding for the contrast tile

When drawing the pill, after the pill surrounds the text, add
horizontal_padding on each side instead of round_rect_padding. This is
the correct value since it is the space between the tile and the text.

Bug: 341217082
Flag: com.android.launcher3.enable_contrast_tiles
Test: Manual, visual change
Change-Id: I48521dc05c04b561b271aa589712ed493af63189