screenShield: Wake up on deactivate()

Usually the screen is woken up before the shield is deactivated, but
it is also possible to unlock the session programmatically via the
org.gnome.ScreenSaver D-Bus API.

The intention is very likely not to unlock a turned off screen in
that case. Nor does it seem like a good idea to change the lock
state without any indication.

Waking up the screen is more likely to meet expectations and is
more reasonable too, so do that.

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1158


(cherry picked from commit fbe2e30f)