[SB][Notif] Only hide `when` in chip if notif was automatically promoted

Bug: 364653005
Flag: com.android.systemui.promote_notifications_automatically
Flag: com.android.systemui.status_bar_notification_chips
Test: Trigger normally promoted notif -> verify it shows `when` time
Test: Trigger automatically promoted notif -> verify it doesn't show
`when` time
Test: atest NotifChipsViewModelTest

Change-Id: Ie84f082436c17e12b29e9f7a37bdaf4bae3c61a8