Use ALT_INSTANCE_USER for image_alt_ssh_user
Use ALT_INSTANCE_USER for image_alt_ssh_user

Change-Id: Ib9cfb6e989575d62c493cbe92fdefd8c90256bcd
Closes-Bug: 1377914

olivierlemasle/devstack,avvocatodemarchis/devstack,liuquansheng47/devstack,upadhyay-prashant/devstack,nawawi/openstack,mssumanth/devstack,upadhyay-prashant/devstack,parul24/devstack,LoHChina/devstack,TwinkleChawla/devstack,prithivm/branch01,bljgaurav/openstack-test,mc2014/devstack,andrewrothstein/devstack,noironetworks/devstack,costingalan/devstack,varunarya10/devstack,liuquansheng47/devstack,group-policy/devstack,nuxeh/devstack,avvocatodemarchis/devstack,pczerkas/devstack,rushiagr/devstack,rushiagr/devstack,promptworks/devstack,eharney/devstack,BSJAIN92/OpenStack,bq-xiao/devstack,ozamiatin/devstack,samgoon/devstack,dtroyer/devstack,dirkmueller/devstack,bswartz/devstack,pacinete/devstack,openstack-dev/devstack,nawawi/openstack,atulpatil301/devstack,prithivm/branch01,affo/devstack,ozamiatin/devstack,Mahito/devstack,dirkmueller/devstack,kplus/devstack-moonshot,pacinete/devstack,olivierlemasle/devstack,eharney/devstack,sequenceiq/devstack,atulpatil301/devstack,bljgaurav/openstack-test,bigswitch/devstack,pombredanne/devstack,dtroyer/devstack,promptworks/devstack,richliu/devstack,mmasaki/devstack,mc2014/devstack,CloudServer/devstack,flavio-fernandes/devstack,LoHChina/devstack,pczerkas/devstack,sequenceiq/devstack,samgoon/devstack,herrsechs/devstack,vishnugonela/devstack,wenhuizhang/devstack,richliu/devstack,mmasaki/devstack,costingalan/devstack,thomasem/devstack,herrsechs/devstack,HPCHub/devstack,CloudServer/devstack,TwinkleChawla/devstack,neerja28/Devstack_GlusterFS,vishnugonela/devstack,pombredanne/devstack,j4/devstack,kplus/devstack-moonshot,bq-xiao/devstack,bigswitch/devstack,mssumanth/devstack,sc68cal/devstack,flavio-fernandes/devstack,thomasem/devstack,noironetworks/devstack,wenhuizhang/devstack,j4/devstack,vsham20/devstack,parul24/devstack,vsham20/devstack,neerja28/Devstack_GlusterFS,varunarya10/devstack,group-policy/devstack,BSJAIN92/OpenStack,HPCHub/devstack,nuxeh/devstack,andrewrothstein/devstack,NaokiMiyata/devstack,bswartz/devstack,sc68cal/devstack,openstack-dev/devstack,Mahito/devstack,NaokiMiyata/devstack,affo/devstack