selftest: Prime the netlogon cache during test_idmap_rfc2307

selftest: Prime the netlogon cache during test_idmap_rfc2307

This ensures that the group memberships just created are reflected in the test
comparison.  Otherwise we are trusting that no caches are primed, which is
simply not safe in a test.

(The login will put a list of groups, as obtained by the login over NETLOGON or
via the PAC, into the samlogon cache).

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Sun Jul  2 21:59:18 CEST 2017 on sn-devel-144