minor: remove useless subscription from BGP peer for IPv4/RTC:<specific-RT>
minor: remove useless subscription from BGP peer for IPv4/RTC:<specific-RT>

stackforge/networking-bagpipe-l2,stackforge/networking-bagpipe-l2,openstack/networking-bagpipe-l2,openstack/networking-bagpipe,murat1985/bagpipe-bgp,openstack/networking-bagpipe,openstack/networking-bagpipe-l2,murat1985/bagpipe-bgp