openstack builder: Set image_type to "image"
openstack builder: Set image_type to "image"

so that built images are treated as images and not as snapshots.

Fixes: GH-3038

dave2/packer,mwhooker/packer,taliesins/packer,pieter-lazzaro/packer,mefellows/packer,hashicorp/packer,arizvisa/packer,tb3088/packer,youhong316/packer,arizvisa/packer,grange74/packer,timsutton/packer,grubernaut/packer,rnaveiras/packer,paulmey/packer,life360/packer,legal90/packer,pvanbuijtene/packer,jimmythedog/packer,taliesins/packer,ricardclau/packer,pieter-lazzaro/packer,youhong316/packer,mkuzmin/packer,dayglojesus/packer,smaato/packer,KohlsTechnology/packer,dave2/packer,smaato/packer,grubernaut/packer,tsmolka/packer,mohae/packer,jimmythedog/packer,mayflower/packer,dantran/packer,pecigonzalo/packer,hashicorp/packer,bhcleek/packer,sean-/packer,sean-/packer,timsutton/packer,routelastresort/packer,smaato/packer,grubernaut/packer,tb3088/packer,vtolstov/packer,sean-/packer,jen20/packer,monkeylittleinc/packer,pvanbuijtene/packer,pvanbuijtene/packer,life360/packer,p1-nico/packer,c22/packer,routelastresort/packer,mefellows/packer,rnaveiras/packer,ricardclau/packer,mafrosis/packer,ricardclau/packer,mefellows/packer,markpeek/packer,paulmey/packer,smaato/packer,tsmolka/packer,c22/packer,pieter-lazzaro/packer,dave2/packer,tas50/packer,danschaffer/packer,monkeylittleinc/packer,mayflower/packer,grubernaut/packer,rnaveiras/packer,rnaveiras/packer,tas50/packer,yoctocloud/packer,dave2/packer,pecigonzalo/packer,KohlsTechnology/packer,quantang/packer,bhcleek/packer,mitchellh/packer,mwhooker/packer,atlassian/packer,routelastresort/packer,quantang/packer,pieter-lazzaro/packer,pvanbuijtene/packer,paulmey/packer,marc-ta/packer,dayglojesus/packer,c22/packer,ephemeralsnow/packer,timsutton/packer,zhuzhih2017/packer,bryson/packer,c22/packer,pvandervelde/packer,vtolstov/packer,ephemeralsnow/packer,sean-/packer,grubernaut/packer,bhcleek/packer,mafrosis/packer,c22/packer,mohae/packer,p1-nico/packer,samdunne/packer,samdunne/packer,esemplare/packer,tas50/packer,ricardclau/packer,mitchellh/packer,mohae/packer,jen20/packer,youhong316/packer,atlassian/packer,ChrisLundquist/packer,tsmolka/packer,smaato/packer,mwhooker/packer,mwhooker/packer,tas50/packer,mansunkuo/packer,atlassian/packer,yoctocloud/packer,paulmey/packer,atlassian/packer,marc-ta/packer,yoctocloud/packer,grange74/packer,p1-nico/packer,ricardclau/packer,tsmolka/packer,mkuzmin/packer,monkeylittleinc/packer,KohlsTechnology/packer,boumenot/packer,ChrisLundquist/packer,bryson/packer,Akasurde/packer,sneal/packer,mitchellh/packer,samdunne/packer,dantran/packer,pieter-lazzaro/packer,p1-nico/packer,monkeylittleinc/packer,ephemeralsnow/packer,markpeek/packer,ChrisLundquist/packer,threatstream/packer,bryson/packer,legal90/packer,mkuzmin/packer,dayglojesus/packer,samdunne/packer,hashicorp/packer,jen20/packer,rickard-von-essen/packer,arizvisa/packer,bryson/packer,life360/packer,tsmolka/packer,danschaffer/packer,timsutton/packer,dave2/packer,pvanbuijtene/packer,mkuzmin/packer,Akasurde/packer,dantran/packer,sneal/packer,bryson/packer,mwhooker/packer,mayflower/packer,arizvisa/packer,jen20/packer,paulmey/packer,marc-ta/packer,markpeek/packer,ChrisLundquist/packer,Akasurde/packer,danschaffer/packer,mayflower/packer,markpeek/packer,dave2/packer,zhuzhih2017/packer,zhuzhih2017/packer,mafrosis/packer,mitchellh/packer,atlassian/packer,sneal/packer,zhuzhih2017/packer,sean-/packer,life360/packer,Akasurde/packer,pvandervelde/packer,rickard-von-essen/packer,quantang/packer,mafrosis/packer,esemplare/packer,dantran/packer,c22/packer,rickard-von-essen/packer,tas50/packer,boumenot/packer,pecigonzalo/packer,jimmythedog/packer,mayflower/packer,youhong316/packer,youhong316/packer,grange74/packer,mkuzmin/packer,atlassian/packer,life360/packer,danschaffer/packer,zhuzhih2017/packer,timsutton/packer,tb3088/packer,rnaveiras/packer,sneal/packer,smaato/packer,KohlsTechnology/packer,jen20/packer,mafrosis/packer,grubernaut/packer,KohlsTechnology/packer,boumenot/packer,tb3088/packer,tb3088/packer,mkuzmin/packer,taliesins/packer,esemplare/packer,paulmey/packer,legal90/packer,zhuzhih2017/packer,pieter-lazzaro/packer,tas50/packer,mansunkuo/packer,yoctocloud/packer,timsutton/packer,ChrisLundquist/packer,mansunkuo/packer,esemplare/packer,arizvisa/packer,pecigonzalo/packer,markpeek/packer,quantang/packer,mohae/packer,yoctocloud/packer,taliesins/packer,routelastresort/packer,marc-ta/packer,vtolstov/packer,ricardclau/packer,p1-nico/packer,dayglojesus/packer,boumenot/packer,esemplare/packer,rnaveiras/packer,mefellows/packer,taliesins/packer,p1-nico/packer,vtolstov/packer,threatstream/packer,legal90/packer,markpeek/packer,bhcleek/packer,boumenot/packer,rickard-von-essen/packer,dayglojesus/packer,legal90/packer,KohlsTechnology/packer,pvandervelde/packer,rickard-von-essen/packer,quantang/packer,hashicorp/packer,samdunne/packer,grange74/packer,threatstream/packer,jimmythedog/packer,tsmolka/packer,arizvisa/packer,taliesins/packer,youhong316/packer,sean-/packer,threatstream/packer,pvandervelde/packer,grange74/packer,mansunkuo/packer,pvandervelde/packer,Akasurde/packer,mohae/packer,monkeylittleinc/packer,pvandervelde/packer,threatstream/packer,vtolstov/packer,jimmythedog/packer,sneal/packer,mitchellh/packer,ephemeralsnow/packer,dantran/packer,routelastresort/packer,ChrisLundquist/packer,tb3088/packer,bhcleek/packer,danschaffer/packer,ephemeralsnow/packer,bryson/packer,mansunkuo/packer,jen20/packer