selftest:Samba3: call "net primarytrust dumpinfo" setup_nt4_member() after the join

selftest:Samba3: call "net primarytrust dumpinfo" setup_nt4_member() after the join

Here we check that we get 'REDACTED SECRET VALUES' printed, in order
to avoid regression on the non '-f' behavior.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12782

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
(cherry picked from commit 9530284383f252efd64bfdf138579964c6500eba)

Autobuild-User(v4-5-test): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(v4-5-test): Thu Jul 13 15:03:29 CEST 2017 on sn-devel-144