libvirt.test: Improve virsh setmem test for lxc

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
libvirt.test: Improve virsh setmaxmem test for lxc

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
libvirt.test: Improve virsh schedinfo test for lxc

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>