Fix small positioning bug with DWB banner in landscape

The DWB banner is now positioned correctly when the task thumbnail is set as a secondary split view.

Fixes: 220637396
Test: Manual testing on local Pixel 6
Change-Id: I3bcb0eb09d2a607b2891bc9f63f3a0b03668f48e
(cherry picked from commit 87fad7b9)