ovn-base: Create /run/ovn in extend_start.sh

OVN 2.12 packages are not creating /run/ovn directory,
which is the default socket/pidfile path for ovn services.

Change-Id: I9cf8c9a4fafeab00f76ee70a123b9a841aa77512

docker/ovn/ovn-base/extend_start.sh

@@ -1,5 +1,8 @@
 #!/bin/bash
 
+if [[ ! -d "/run/ovn" ]]; then
+    mkdir -p /run/ovn
+fi
 if [[ ! -d "/var/log/kolla/openvswitch" ]]; then
     mkdir -p /var/log/kolla/openvswitch
 fi