selftest: Make chgdcpass's NTVFS usage more obvious

selftest: Make chgdcpass's NTVFS usage more obvious

The chgdcpass testenv was not passing --use-ntvfs to the provision
command, but it was still actually using NTVFS.

The reason is the smb.conf generated by provision_raw_step1() would
always try to use the s4/NTVFS file server. Because the smb.conf already
existed, this trumped what was passed to the provision command.

This patch doesn't change the chgdcpass file server. It just makes it
more obvious that chgdcpass is using NTVFS.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13676

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>