Restrict available LDAP servers.

You can view any available LDAP if you have access
to the root entity.

Otherwise, only the LDAP configured as the default
for the current entity is displayed.

inc/question.class.php

@@ -836,8 +836,15 @@ public function showForm($ID, $options = []) {
       if ($ldap_values === null) {
          $ldap_values = [];
       }
+      $current_entity = $_SESSION['glpiactive_entity'];
+      if ($current_entity == 0) {
+         $auth_ldap_condition = '';
+      } else {
+         $auth_ldap_condition = "glpi_authldaps.id = (select glpi_entities.authldaps_id from glpi_entities where id=${current_entity})";
+      }
       Dropdown::show('AuthLDAP', [
          'name'      => 'ldap_auth',
+         'condition' => $auth_ldap_condition,
          'rand'      => $rand,
          'value'     => (isset($ldap_values['ldap_auth'])) ? $ldap_values['ldap_auth'] : '',
          'on_change' => 'change_LDAP(this)',