In this latest episode of `Which CI job has lyarwood broken today?!` we
find that I464bc2b88123a012cd12213beac4b572c3c20a56 introduced a
regression in the nova-lvm experimental job as n-cpu attempted to run
qemu-img info against block devices as an unprivileged user.
For the time being we should skip any attempt to use this command
against block devices until the disk_api layer can make privileged
calls using privsep.
Closes-bug: #1771700
Change-Id: I9653f81ec716f80eb638810f65e2d3cdfeedaa22
(cherry picked from commit fda48219a3)