Check StatusBarState in shouldShowEmptyShadeView.

Both the empty shade and the footer independently had different bugs
filed where they were showing up during aod/keyguard transitions. In the
old code, these were fixed in slightly different ways by different
people, but the root cause of these bugs was actually the same. Now that
we have these checks in one place, it's become clear that we can
actually check for the same conditions to make sure the empty shade and
the footer aren't showing when the device is locked (unless the shade is
open on top).

Bottom line is, although the old code was checking for specific
transitions to avoid showing the empty shade, these were just specific
edge cases we found and fixed individually. Instead of checking for edge
cases (and potentially risking new edge cases showing up), it's more
effective to simply define that the empty shade should never be showing
on the keyguard.

Bug: 293167744
Test: NotificationListViewModelTest + checked repro steps from
b/228790482 and b/267060171 to make sure there's no regression
Flag: ACONFIG com.android.systemui.notifications_footer_view_refactor STAGING

Change-Id: Ifc38554eab7acaa11333cf2a2516fb3e0b3e07ee