Add /run/frr volume mount
Add /run/frr volume mount

Having /var/frr mounted between the host and the FRR container enables
the host as well as adjacent containers (e.g. OVN BGP agent) to control
FRR with the vtysh CLI through the vty socket.

  $ vtysh --vty_socket /run/frr

Change-Id: Ib9ca7e1f56cf4fe6d63807cd4e5e58ee91501a5f

openstack/tripleo-heat-templates,openstack/tripleo-heat-templates