qemu: Remove managed save flag from VM when starting with --force-boot
qemu: Remove managed save flag from VM when starting with --force-boot

https://bugzilla.redhat.com/show_bug.cgi?id=917510

At the start of the guest after the image is unlinked the state wasn't
touched up to match the state on disk.
(cherry picked from commit 9933a6b2fa8182d8ec676f7f7f00af7063a387f9)

mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2,mithleshvrts/libvirt-0.10.2