tasks: lxc_net: Do not source non-existing network script on CentOS
tasks: lxc_net: Do not source non-existing network script on CentOS

Commit 53a6cce9ed08 ("Use handlers to restart services and move dnsmasq
to a unit file") removed the ifup-post script on CentOS but we are still
sourcing it in the main network script and it's causing problems when
trying to bring the lxcbr0 interface up.

[root@localhost network-scripts]# ifup lxcbr0
RTNETLINK answers: File exists
/etc/sysconfig/network-scripts/ifup-post: line 115: /etc/sysconfig/network-scripts/ifup-post-lxcbr0: No such file or directory

Change-Id: Icf788fd82e298b7e17e784e0d27898f93e7441aa

openstack/openstack-ansible-lxc_hosts,openstack/openstack-ansible-lxc_hosts