dsdb: Set syntax of userParameters to binary string, not unicode string

dsdb: Set syntax of userParameters to binary string, not unicode string

This means we continue to store the values as given on SAMR, assuming
that the SAMR buffer is little endian.  The syntax for this specific
object is forced to be a binary blob, so that it is not converted on
DRSUAPI.

This commit does not fix existing databases, nor pdb_samba_dsdb (used
by classicupgrade).

Andrew Bartlett

Bug: https://bugzilla.samba.org/show_bug.cgi?id=8077
Change-Id: I10bb6aaecc381194e3c0ce6b9163f961acbdcee1
Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>