Remove ml2_conf.ini from ML2 agent init scripts

[Matt Kassawara]

In Liberty onwards, remove ml2_conf.ini from Linux bridge agent init script because configuration resides completely in linuxbridge_agent.ini configuration file.

Likewise, in Newton onwards, remove ml2_conf.ini from the Open vSwitch agent init script because configuration should reside completely within openvswitch_agent.ini config file.

[Kevin Carter (kevin-carter)]

In testing right before the kilo release doing this lead to issues with metadata and agent stability causing us to disable apr spoofing protection in order to pass the gate. I think that the intentions are good in simplifying configs I think there are some issues with it still and sourcing both files simply ensures that all of the appropriate configs are loaded as expected. If there's something that we can do in the various configuration files to make this more feasible than I'm certainly game to make the update however I'd rather error on the side of caution in most cases.

[Travis Truman (travis-truman)]

This bug also applies to the Open vSwitch ML2 agent. See https://openstack.nimeyo.com/94783/openstack-operators-puppet-neutron-mitaka-config-mismatch