[octane] copy_vips works improperly for 6.X clusters

[Roman Sokolkov]

6.X clusters doesn't have VIP namespace stored in DB. So after copy_vips deployment fails, because no namespace for VIPs.

Steps to reproduce:
- Deploy 6.1
- Upgrade Fuel to 9.1
- execute octane upgrade-node --isolated for controller (don't wait until finished)
- fuel vip --download --env $SEED_ENV

Actual result:
[root@fuelsrv001 ~]# grep -r vip_namespace /root/vips_2.yaml
  vip_namespace: vrouter
  vip_namespace: null
  vip_namespace: null
  vip_namespace: null

Expected result:
[root@fuelsrv001 ~]# grep -r vip_namespace /root/vips_2.yaml
  vip_namespace: vrouter
  vip_namespace: vrouter
  vip_namespace: haproxy
  vip_namespace: haproxy

[Roman Sokolkov (rsokolkov)]

Merged to stable/mitaka https://review.openstack.org/#/c/407911/

Merged to master https://review.openstack.org/#/c/407910/