qemu: Restore original memory locking limit on reconnect

qemu: Restore original memory locking limit on reconnect

Commit v8.4.0-287-gd4d3bb8130 tried to make sure the original
pre-migration memory locking limit is restored at the end of migration,
but it missed the case when libvirt daemon is restarted during
migration which needs to be aborted on reconnect.

And if this was not enough, I forgot to actually save the status XML
after setting the field in priv (in the commit mentioned above and also
in v8.4.0-291-gd375993ab3).

https://bugzilla.redhat.com/show_bug.cgi?id=2107424

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>