SAMBA ONLY krb5: Don't generate PAC_ATTRIBUTES_INFO and UPN_DNS_INFO buffers

SAMBA ONLY krb5: Don't generate PAC_ATTRIBUTES_INFO and UPN_DNS_INFO buffers

Currently we leave it up to the plugin to generate them, which allows
more control over what situations they are included in.

[abartlet@samba.org This commit makes the check-context test fail, but
is critical to how Samba operates an AD DC, because Samba wants full
control of the buffers here.  A way to make this behaviour
optional would be useful in the future]

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>