silence "Can not convert group sid" warnings in the log

silence "Can not convert group sid" warnings in the log

/var/log/samba/log.winbind is full of messages like:

[2024/02/09 06:25:04.788182,  1, pid=74620] source3/winbindd/winbindd_getgroups.c:259(winbindd_getgroups_recv)
  Could not convert sid S-0-0: NT_STATUS_NONE_MAPPED

On a busy server these are logged several 1000s times per minute,
making any other messages basically invisible.

This is a work-around, a proper solution is to handle some
special SIDs (like this one) separately.  Once this is done,
this change can be reverted.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Pavel Filipenský <pfilipensky@samba.org>