ldap2: modify arguments for create_connection
* Remove unused and obsolete function arguments:
* tls_certfile
* tls_keyfile
* debug_level
* Rename tls_cacertfile to cacert (same as name in LDAPClient)
* Set cacert to constants.CACERT by default.
https://fedorahosted.org/freeipa/ticket/6461
Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>