AnimateKeyguardInDelay should use the animator duration scale

Additionally, be defensive about showing the keyguard after
screen off in case something is holding up the choreography
and the light reveal finishes before the keyguard gets a chance
to animate in.

Bug: 194812424
Test:
  1. manually set animator duration to .5
  2. go to home screen
  3. press power button for device to go into doze
  4. check systemui logs that dozing=true
Change-Id: Iae4498189a61fa9d8fa78ef4888aea840eaf3682