Re: [all][dev][qa] cirros 0.5.1

Hello OpenStack Folks! Since it's early in the Victoria cycle, it's a good time to revisit the cirros 0.5.1 migration in common CI. The patch [1] is getting a cleanup due to nova fix increasing instance memory limits upfront but I propose to merge it as soon as we clean it up properly. It has been tested with Ussuri in Kolla CI and had positive results from Tempest jobs for Neutron and Ironic. It would be great if we made sure projects no longer use the old cirros 0.4.0 nor some old Ubuntus. [1] https://review.opendev.org/711492 -yoctozepto