tests/ldap: Use TLDAP to check the extended DN return

tests/ldap: Use TLDAP to check the extended DN return

Tests commit 9f6b87d3f6cc9930d75c1f8d38ad4f5a37da34ab

To run: make test TESTS="samba3.smbtorture_s3.plain.TLDAP"

Reverting the above commit makes this test fail:

'GUID format in control (no hyphens) doesn't match output
tldap_search with extended dn (no val) failed: LDAP error 0 (TLDAP_SUCCESS),
TEST TLDAP FAILED!'

This behaviour couldn't be tested via LDB libraries because they never
deal with the underlying DN string.

Signed-off-by: Garming Sam <garming@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14029

Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Thu Aug  1 06:20:28 UTC 2019 on sn-devel-184