add an octavia load balancer

[ad2ien]

352

• Add an ocatavia loadbalancer with terraform

• Remove external DNS

• [x] add admin network

• [x] automate LB config with nodes IPs

• [x] parametrize LB floating IP

• [x] Configure DNS entry with terraform (only for non prod envs)

[ad2ien]

Ingress-nginx part will be improved later by #402