[SB][Notif] For auto-promoted notifs, allow fake shortCriticalText.

This CL adds a new extra for automatically promoted notifications that
can be set with fake short critical text.

Bug: 364653005
Flag: com.android.systemui.promote_notifications_automatically
Test: N/A (unused in AOSP)
Change-Id: I413920a0fc0831296a1f9369d746796b17f7f66f