winbindd: use passdb backend for well-known SIDs

winbindd: use passdb backend for well-known SIDs

On a DC well-known SIDs like S-1-1-0 (everyone) *must* be handled by the
local domain, otherwise something simple like this fails with
WBC_ERR_DOMAIN_NOT_FOUND:

$ make testenv SELFTEST_TESTENV=nt4_dc SCREEN=1

localnt4dc2$ ./bin/wbinfo --sid-to-name S-1-1-0
failed to call wbcLookupSid: WBC_ERR_DOMAIN_NOT_FOUND
Could not lookup sid S-1-1-0

On a member server asking our DC works and is what we're currently
doing, but changing it to ask passdb avoids the overhead.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=12727

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>