qemu: Try harder to remove pr-helper object and kill pr-helper process

qemu: Try harder to remove pr-helper object and kill pr-helper process

If libvirt receives DISCONNECTED event and prDaemonRunning is set
to false, and qemuDomainRemoveDiskDevice() is performing in the
meantime, then qemuDomainRemoveDiskDevice() will fail to remove
pr-helper object because prDaemonRunning is false. But removing
that check from qemuHotplugRemoveManagedPR() is not enough,
because after removing the object through monitor the
qemuProcessKillManagedPRDaemon() is called which contains the
same check. Thus the pr-helper process might be left behind.

Signed-off-by: Jie Wang <wangjie88@huawei.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>