Refactor on the QS shade overlay's vertical paddings

This CL removes the verticalArrangement of the columns in the
QS shade overlay. Instead, this CL adds paddings explicitly between
the columns' children. Desktop will apply different vertical
paddings, as a part of the AL UI density project. This CL makes
my subsequent changes easier.

This CL should not make any UI difference. I used HSV to verify it.

Bug: 427487608
Flag: EXEMPT refactor
TEST: manually
Change-Id: I1fa925daafb31bdebde5ca4e3286d2c42a838fa5