samba-tool classicupgrade: Do not print the admin password during upgrade

samba-tool classicupgrade: Do not print the admin password during upgrade

This changes the code to only set and show a new password if no admin
user is found during the upgrade.

Andrew Bartlett

Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Thu Jan 10 16:55:23 CET 2013 on sn-devel-104
(cherry picked from commit 051a1a9c6417c2cbffa7d091ae477a6c7922d363)

Fix bug #samba-tool classicupgrade patch to not print incorrect admin passwords.