Thanks, Slawek, we're planning to use that.

Unfortunately, we can't set that opt for every slow job (a job which runs the test which requires that opt to be set correctly). I tried that (https://review.opendev.org/c/openstack/tempest/+/874586) before I realize there are many variations of jobs which run the test. Plus we can set that opt only for master, the older branches where the new cirros image won't be used can't be affected. That being said, our plan is to address that in Devstack and basically set that opt automatically when cirros > 0.6.0 is used.