Fix hub<->occluded transition when undocked

Currently, if the hub is occluded while undocked, when the occluding
activity is finished, the user will land back on the lockscreen instead
of the hub if the device is undocked.

This is due to the fact that we tie whether or not to show the hub to
the dock signal. Instead, this change updates the logic to always go
back to the hub from the occluded state if we entered the occluded state
from the hub.

Fixes: 338203881
Test: atest CommunalInteractorTest
Test: atest WmShellTest
Test: atest KeyguardTransitionScenariosTest
Flag: ACONFIG com.android.systemui.communal_hub TEAMFOOD
Change-Id: Ic9adf4dba601d4c416e7e18711c7c371117cbb2e