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

Commit 53a6cce ("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

tasks/lxc_net.yml

@@ -56,14 +56,9 @@
 
 - name: Create networking post-up and post-down data for Red Hat
   lineinfile:
-    dest: "{{ item.dest }}"
-    line: "{{ item.line }}"
+    dest: "/etc/sysconfig/network-scripts/ifdown-post"
+    line: ". /etc/sysconfig/network-scripts/ifdown-post-{{ lxc_net_bridge }}"
     insertbefore: "^exit\ 0$"
-  with_items:
-    - dest: "/etc/sysconfig/network-scripts/ifup-post"
-      line: ". /etc/sysconfig/network-scripts/ifup-post-{{ lxc_net_bridge }}"
-    - dest: "/etc/sysconfig/network-scripts/ifdown-post"
-      line: ". /etc/sysconfig/network-scripts/ifdown-post-{{ lxc_net_bridge }}"
   when: ansible_os_family | lower == "redhat"
   notify:
     - Restart bridge