Align taskbar so that it does not overlap with nav buttons.

Fixes: 275510698
Bug: 259712417
Test: View device where taskbar should be start aligned
      Update Display size to make everything bigger
      Observe that taskbar icons never overlap nav buttons
Flag: ENABLE_TRANSIENT_TASKBAR true

Change-Id: I246374518f21c4b92d3e02e5582c929a471d9305