_get_server_floating_ip is not returing a float in all cases

In some cases.. depending on the tenant networking _get_server_floating_ip
was not returning the float. This change properly goes through all networks
and returns the floating ip address.

Change-Id: Ie48b0c48a5969589d921cb5f27b4174422837286
networks in the openstack host env can vary open default ansible_ipv4 for tempest

Noticed in some env default and private are the same address.
Ensure tempest can connect to the controller by openging the
port to the default ipv4 address
"tempest_default_ip": "192.168.40.3"
"tempest_private_ip": "192.168.40.3"
"hostvars[tempest_name].ansible_default_ipv4.address": "192.168.50.3"

Change-Id: I7087701c63906f2a9843a4479947eb4fe8c7fd4e