qemu: blockjob: Don't stop processing the finished job early

qemu: blockjob: Don't stop processing the finished job early

Both failure to refresh and to dismiss the job are very unlikely but if
they happen there's not much we can do about the blockjob.

The concluded job handlers treat it as if the job failed if we don't
update the state to 'QEMU_BLOCKJOB_STATE_COMPLETED' which is probably
the safest thing to do here.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>