Use IPA CA certificate when available and ignore NO_TLS_LDAP when not.
    
    ipa-client-automount is run after ipa-client-install so the CA certificate
    should be available. If the certificate is not available and ipadiscovery.ipacheckldap
    returns NO_TLS_LDAP warn user and try to continue.
    
    https://fedorahosted.org/freeipa/ticket/4902
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>