LDAP: replace deprecated constant

apps/user_ldap/lib/connection.php

@@ -112,7 +112,7 @@ class Connection {
 			$this->config['ldapUserFilter']        = \OCP\Config::getAppValue($this->configID, 'ldap_userlist_filter','objectClass=person');
 			$this->config['ldapGroupFilter']        = \OCP\Config::getAppValue($this->configID, 'ldap_group_filter','(objectClass=posixGroup)');
 			$this->config['ldapLoginFilter']       = \OCP\Config::getAppValue($this->configID, 'ldap_login_filter', '(uid=%uid)');
-			$this->config['ldapGroupDisplayName']  = mb_strtolower(\OCP\Config::getAppValue($this->configID, 'ldap_group_display_name', LDAP_GROUP_DISPLAY_NAME_ATTR), 'UTF-8');
+			$this->config['ldapGroupDisplayName']  = mb_strtolower(\OCP\Config::getAppValue($this->configID, 'ldap_group_display_name', 'uid'), 'UTF-8');
 			$this->config['ldapQuotaAttribute']    = \OCP\Config::getAppValue($this->configID, 'ldap_quota_attr', '');
 			$this->config['ldapQuotaDefault']      = \OCP\Config::getAppValue($this->configID, 'ldap_quota_def', '');
 			$this->config['ldapEmailAttribute']      = \OCP\Config::getAppValue($this->configID, 'ldap_email_attr', '');