[Central Surfaces] NSSLC snoozes with NotificationsController directly.

Removes a CentralSurfaces reference by having NSSLC talk directly to
NotificationsController.

Bug: 277764509
Bug: 277762009
Test: manual: verified NotificationsController still notified when
notification is snoozed
Test: atest NotificationStackScrollLayoutControllerTest
CentralSurfacesImplTest

Change-Id: I2e9948e2c0d0f6677c34b2f3dc758334fbe6289a