s4:torture/ndr: demonstrate the ndr_push_string(STR_NOTERM|REMAINING) of "" is wrong

s4:torture/ndr: demonstrate the ndr_push_string(STR_NOTERM|REMAINING) of "" is wrong

convert_string_talloc() never returns a string with len=0 and always
implies zero termination byte(s).

For ndr_push_string this is unexpected as we need to be compatible on
the wire and push 0 bytes for an empty string.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14956

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
(cherry picked from commit 8da26cb6725b5d853ab481a348a3a672966715b5)