Don't show the altBouncer if isDozing=true

There's strange bouncer behavior where CentralSurfacesImpl
sometimes unexpectedly requests the bouncer when the device
start doing. To protect against showing the bouncer
during the screen off transition, make sure to guard showing the
alternateBouncer on isDozing.

Test: repeatedly unfold & unlock with FP & fold (x10) and observe
that there's no alternate bouncer lingering on display
Test: atest AlternateBouncerInteractorTest
Fixes: 273303575

Change-Id: I6412ed147be5fd6ca9952b65fc39d029babf1233