qemuSecurityRestoreAllLabel: Don't use transactions

qemuSecurityRestoreAllLabel: Don't use transactions

Because of the nature of security driver transactions, it is
impossible to use them properly. The thing is, transactions enter
the domain namespace and commit all the seclabel changes.
However, in RestoreAllLabel() this is impossible - the qemu
process, the only process running in the namespace, is gone. And
thus is the namespace. Therefore we shouldn't use the transactions
as there is no namespace to enter.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>