RoomViewController: Do not display the banner "jump to last unread message" when the timeline is not in live.
RoomViewController: Do not display the banner "jump to last unread message"
when the timeline is not in live.

vector-im/vector-ios,vector-im/riot-ios,vector-im/riot-ios,vector-im/riot-ios,vector-im/riot-ios,vector-im/riot-ios,vector-im/vector-ios,vector-im/riot-ios,vector-im/vector-ios