[Samba] adjust DC name after classicupgrade

[mourik jan heupink]

> Yes, that would be the best approach, once you have a copy of the
> smb3.conf that you are doing the import with on your new vm, give it the
> new name.  Because there traditionally isn't a trust account for the PDC
> in it's own domain in 'classic' domains, there is nothing to conflict
> with at this point, and you can then join the file server under the name
> fileserver.
>
> Andrew Bartlett

Thank you, Andrew & everyone who responded.