Revive BaseLinuxTestCase._create_namespace
Revive BaseLinuxTestCase._create_namespace

It was removed by commit 7f7343b1afc0b1b953e5c36a753397a6d37316cb
but still have a few users.

Closes-Bug: #1446465
Change-Id: I2914700f17ae38a775735906931f0f616c13c602

wenhuizhang/neutron,barnsnake351/neutron,jacknjzhou/neutron,mandeepdhami/neutron,neoareslinux/neutron,sebrandon1/neutron,JioCloud/neutron,cloudbase/neutron,eonpatapon/neutron,shahbazn/neutron,yanheven/neutron,chitr/neutron,antonioUnina/neutron,skyddv/neutron,NeCTAR-RC/neutron,neoareslinux/neutron,skyddv/neutron,sasukeh/neutron,jerryz1982/neutron,openstack/neutron,wolverineav/neutron,openstack/neutron,JianyuWang/neutron,openstack/neutron,eayunstack/neutron,NeCTAR-RC/neutron,swdream/neutron,bigswitch/neutron,javaos74/neutron,igor-toga/local-snat,dhanunjaya/neutron,wolverineav/neutron,jumpojoy/neutron,mahak/neutron,swdream/neutron,dims/neutron,eayunstack/neutron,aristanetworks/neutron,mmnelemane/neutron,vivekanand1101/neutron,cisco-openstack/neutron,wenhuizhang/neutron,cisco-openstack/neutron,paninetworks/neutron,yanheven/neutron,dims/neutron,silenci/neutron,mahak/neutron,eonpatapon/neutron,SmartInfrastructures/neutron,klmitch/neutron,bigswitch/neutron,asgard-lab/neutron,asgard-lab/neutron,antonioUnina/neutron,SamYaple/neutron,glove747/liberty-neutron,noironetworks/neutron,aristanetworks/neutron,apporc/neutron,MaximNevrov/neutron,adelina-t/neutron,dhanunjaya/neutron,suneeth51/neutron,takeshineshiro/neutron,glove747/liberty-neutron,mmnelemane/neutron,vivekanand1101/neutron,jerryz1982/neutron,sebrandon1/neutron,miyakz1192/neutron,bgxavier/neutron,bgxavier/neutron,noironetworks/neutron,takeshineshiro/neutron,javaos74/neutron,suneeth51/neutron,yuewko/neutron,SmartInfrastructures/neutron,klmitch/neutron,cloudbase/neutron,igor-toga/local-snat,infobloxopen/neutron,barnsnake351/neutron,MaximNevrov/neutron,mandeepdhami/neutron,SamYaple/neutron,adelina-t/neutron,sasukeh/neutron,mattt416/neutron,miyakz1192/neutron,paninetworks/neutron,huntxu/neutron,watonyweng/neutron,watonyweng/neutron,mattt416/neutron,infobloxopen/neutron,silenci/neutron,yuewko/neutron,JioCloud/neutron,shahbazn/neutron,mahak/neutron,huntxu/neutron,JianyuWang/neutron,apporc/neutron,jacknjzhou/neutron,jumpojoy/neutron,chitr/neutron