after the changes around live-iso and qcow2 test cases the asserts
used have also changed. This commit utilizes the existing test lib.
Cherry-picked from d67745d755
Related: rhbz#1769525
Use anaconda to install the root.tar.xz into a disk image. Copy the
disk image to the host, and use the cockpit vm support to boot it and
test it.
Cherry-picked from 4705ff3b1e
Related: rhbz#1769525