[flexiglass] Cleans up some Communal swipe gestures

Removes Dream --> Communal
Changes Communal --> Home to Communal --> Lockscreen

Flag: com.android.systemui.scene_container
Test: unit tests pass
Test: manually started Communal from lockscreen shortcut and tested that
swiping right goes to the lockscreen
Bug: 394159837

Change-Id: Ie5bcd58e9092a20320eb23e13b7459abf0122651