Add service ordering to cleanup service to avoid conflicts with agent startup

If the port cleanup takes too long, the neutron agents might begin
operations on the ovs bridges while cleanup is still ongoing. This can
cause undefined behavior and errors in the agent.

Change-Id: Ia0e31c9469033c50a8b65af7fee1adf03b22d4c2
Closes-Bug: #1913623

deployment/neutron/neutron-cleanup.service

@@ -1,7 +1,7 @@
 [Unit]
 Description=Neutron cleanup on startup
 After=openvswitch.service network.target
-Before=docker.service
+Before=tripleo_neutron_ovs_agent.service tripleo_neutron_dhcp.service tripleo_neutron_l3_agent.service tripleo_nova_compute.service
 RefuseManualStop=yes
 
 [Service]