Shorten and center TaskMenuView for landscape

* The width of the task menu view for landscape
(both fake and real) is the same as the width
it would be in portrait.
* With the shorter width, we also center the
positioning of the TaskMenuView
* Note this is only for phone, large screen
changes TODO

Bug: 193432925
Test: Tested real/fake landscape + seascape,
view is centered. Portrait same as before.

Change-Id: Ide41e252a3c177c4a911aab544f78930fed2e76f