net/openldap26-{server,client}: fix proper usage of FETCH/GSSAPI options

• FETCH_DESC is not present with client
• FETCH applies to *both* client and server since both slapd and client tools use ldif_parse_line2() via libldap which can use libfetch
• GSSAPI is also required for the client as well since ldap*(1) commands can be used to connect and authenticate to directory servers like Active Directory and OpenLDAP with Kerberos via SASL GSSAPI mechanism

PR: ports/267056