Assist: Only call lockscreenShown when it is actually shown

Fixes an issue where lockscreenShown called during onStartedWakingUp. Instead,
we now call it only when the lockscreen is actually shown, not when the layout
is requested for doze.

Change-Id: Idd196bf4fd5027e64a872ac8c0387531e8f59606
Fixes: 64141781
Test: Trigger Elmyra from AOD, verify Assistant shows.
1 file changed