Workaround for bz1535973
Workaround for bz1535973

For some CPU (see [1]) usage of the libguestfs-test-tool's can
fail with Kernel Panic error.

This patch provides workaround and sets libguestfs background to
skip usage of the kvm.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1535973

RHOSINFRA-2130

Change-Id: I1b7871fdf88c19181d235e22b874066448428ce7

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared