Stop using all ports option w/ neutron-ovs-cleanup

Now that our OVS bridge network configs are persistent on reboot
we no longer need to do this to make DHCP work.

Running neutron-ovs-cleanup to cleanup just the neutron generated
ports on reboot is now sufficient.

Change-Id: I42d528b0f58a2ec394d4e01bb02bbf0974e2c3af
Merge "Stop using all ports option w/ neutron-ovs-cleanup"