Use a separate dir for vhost_user sockets

Currently when OVS-DPDK is enabled, instances fail to spawn
due to permissions mismatch, see nova bug for details:
https://bugs.launchpad.net/nova/+bug/1670950

This patch updates openvswitch agent config to use a separate
directory for the sockets. Nova formula patch:
https://gerrit.mcp.mirantis.net/#/c/11213/ takes care
of creating the dir with proper permissions.

Corresponding reclass-system patch is:
https://gerrit.mcp.mirantis.net/13307/

Related-PROD: PROD-14413

Change-Id: I9fdc12ec4c99a517a1ea4e7aba86692529b76c96
4 files changed