In case of a multicell deployment the mysql and nova novncproxy
backend servers need to use the SERVICE_cell_node_names.
Also the novncproxy did use the nova_api_vip and
nova_api_node_[ips|names] information insteand of
nova_vnc_proxy_vip and nova_vnc_proxy_node_[ips|names]
Change-Id: I606d1187a442c6ef6327a7503b6b5f0832cbb872
Related-Bug: #1822607