Fixup neutron constraints in older overclouds before updating

Fixup neutron constraints in older overclouds before updating

The neutron pcs constraints were reworked in
https://review.openstack.org/#/c/229466/

For overclouds deployed with older tripleo-heat-templates the
current pcs ordering constraints will not have those changes,
meaning that the behaviour discussed at
https://bugs.launchpad.net/tripleo/+bug/1501378 is likely
given we will stop and restart all services. This review
applies those, in short, remove the ovs-cleanup after
neutron-server and add openvswitch-agent instead. Detail in
the bug report and linked BZ.

Change-Id: I45822c5fe9029f11635400b7fbd386880ac80a4e
Related-Bug: 1501378