Make sure to remove NotificationShade surface when keyguard went away.

When unlock animation is finished, SysUI clears FLAG_SHOW_WALLPAPER
flag from the NotificationShade window to change wallpaper target
from NotificationShade to Launcher, and make NotificationShade window
invisible.

Wallpaper target change must be processed before disposing surface
of NotificationShade.

Bug: 186984629
Bug: 166736690
Test: manual, enabled remote animation and unlock the device.
Change-Id: Id4c2ae65d9dd5aa903c1a25c920df6ed12a1ba1d