Drop RpcProxy usage from metering_agent
Drop RpcProxy usage from metering_agent

Drop one more use of the RpcProxy compatibility class in favor of
direct use of oslo.messaging APIs.

Part of blueprint drop-rpc-compat.

Change-Id: I3c68aa246d88447f793aa9890f10f5043a41338d

jerryz1982/neutron,NeCTAR-RC/neutron,leeseuljeong/leeseulstack_neutron,swdream/neutron,mahak/neutron,bgxavier/neutron,mattt416/neutron,SamYaple/neutron,CiscoSystems/neutron,paninetworks/neutron,projectcalico/calico-neutron,apporc/neutron,mahak/neutron,silenci/neutron,vivekanand1101/neutron,mmnelemane/neutron,neoareslinux/neutron,chitr/neutron,paninetworks/neutron,wenhuizhang/neutron,klmitch/neutron,Metaswitch/calico-neutron,suneeth51/neutron,takeshineshiro/neutron,jumpojoy/neutron,gkotton/neutron,yuewko/neutron,openstack/neutron,dhanunjaya/neutron,asgard-lab/neutron,chitr/neutron,aristanetworks/neutron,dims/neutron,leeseuljeong/leeseulstack_neutron,cloudbase/neutron-virtualbox,infobloxopen/neutron,CiscoSystems/neutron,eonpatapon/neutron,yuewko/neutron,wenhuizhang/neutron,gkotton/neutron,eayunstack/neutron,bigswitch/neutron,leeseulstack/openstack,asgard-lab/neutron,barnsnake351/neutron,pnavarro/neutron,adelina-t/neutron,jacknjzhou/neutron,antonioUnina/neutron,openstack/neutron,klmitch/neutron,noironetworks/neutron,MaximNevrov/neutron,SamYaple/neutron,alexandrucoman/vbox-neutron-agent,yanheven/neutron,barnsnake351/neutron,miyakz1192/neutron,magic0704/neutron,huntxu/neutron,leeseuljeong/leeseulstack_neutron,cloudbase/neutron,shahbazn/neutron,vveerava/Openstack,neoareslinux/neutron,Metaswitch/calico-neutron,cisco-openstack/neutron,mandeepdhami/neutron,bigswitch/neutron,vivekanand1101/neutron,blueboxgroup/neutron,alexandrucoman/vbox-neutron-agent,skyddv/neutron,Stavitsky/neutron,glove747/liberty-neutron,cloudbase/neutron-virtualbox,sasukeh/neutron,blueboxgroup/neutron,openstack/neutron,SmartInfrastructures/neutron,swdream/neutron,eayunstack/neutron,suneeth51/neutron,watonyweng/neutron,adelina-t/neutron,magic0704/neutron,NeCTAR-RC/neutron,JianyuWang/neutron,Stavitsky/neutron,waltBB/neutron_read,MaximNevrov/neutron,wolverineav/neutron,huntxu/neutron,jerryz1982/neutron,jacknjzhou/neutron,igor-toga/local-snat,bgxavier/neutron,skyddv/neutron,sasukeh/neutron,leeseulstack/openstack,javaos74/neutron,eonpatapon/neutron,silenci/neutron,mandeepdhami/neutron,gkotton/neutron,leeseulstack/openstack,mmnelemane/neutron,infobloxopen/neutron,takeshineshiro/neutron,jumpojoy/neutron,blueboxgroup/neutron,SmartInfrastructures/neutron,igor-toga/local-snat,wolverineav/neutron,mahak/neutron,CiscoSystems/neutron,apporc/neutron,JioCloud/neutron,watonyweng/neutron,sebrandon1/neutron,sebrandon1/neutron,cloudbase/neutron,miyakz1192/neutron,dhanunjaya/neutron,javaos74/neutron,JianyuWang/neutron,dims/neutron,vveerava/Openstack,vveerava/Openstack,noironetworks/neutron,aristanetworks/neutron,rdo-management/neutron,antonioUnina/neutron,waltBB/neutron_read,shahbazn/neutron,pnavarro/neutron,glove747/liberty-neutron,rdo-management/neutron,cisco-openstack/neutron,JioCloud/neutron,yanheven/neutron,projectcalico/calico-neutron,mattt416/neutron