As discussed in the bug the only advice we've been given from the
libvirt and QEMU teams is to avoid this in Bionic where QEMU is using
the legacy -drive architecture. This is passing in the new zuulv3 Focal
based job so just skip the test here for the time being in grenade.
Change-Id: I1aeab16e2b8d907a114ed22c7e716f534fe1b129
Related-Bug: #1901739