[Status Bar Refactor] Remove some cruft from

NotificationShadeWindowViewController.

Not directly related to status bar refactor, but I will touch this class
in a later CL for status bar refactor work so figured I could clean it
up a bit beforehand.

Bug: 209005990
Test: NotificationShadeWindowViewTest
Test: manual
Change-Id: Ie690b6a60327853842ca00729e8f1c94ae96325c