Fix the settings app launch animation

This CL fixes the settings app launch by making sure that the button
mask radius is the same as the actual button. For some reason I used the
wrong dimension in http://ag/14138465, which at the time was the same as
qs_footer_action_corner_radius but was recently changed in
http://ag/14647015.

Bug: 172050985
Test: Click the settings gear button
Change-Id: I2a02ab177c72cbd0919095167254546e25ce2e5f