nova: Stop setting '[DEFAULT] use_ipv6'

Change I188fc2cd1b26fe7a71804f7e7d66b111d6f15e30 in nova stopped us
respecting this when generating the network templates injected into
instances on boot. With the removal of nova-network, there is no longer
any other reason to set this.

Change-Id: I925b7c6c23133cd5a835960f4507c979f615d78e
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

Author: stephenfin

lib/nova

@@ -391,7 +391,6 @@ function create_nova_conf {
     iniset $NOVA_CONF neutron default_floating_pool "$PUBLIC_NETWORK_NAME"
     if [[ $SERVICE_IP_VERSION == 6 ]]; then
         iniset $NOVA_CONF DEFAULT my_ip "$HOST_IPV6"
-        iniset $NOVA_CONF DEFAULT use_ipv6 "True"
     else
         iniset $NOVA_CONF DEFAULT my_ip "$HOST_IP"
     fi