remove devstack/create_magnum_conf_magnum_network
remove devstack/create_magnum_conf_magnum_network

Looks like this function was not in use ever.
It adds nova networking related options to the magnum.conf,
which normally would belong to the nova.conf.

Change-Id: I8435c674db17af2d0641afcf3cab140830130784

ArchiFleKs/magnum,openstack/magnum,jay-lau/magnum,ArchiFleKs/magnum,openstack/magnum