fix(glpiselectfield): comparisons need to properly find the itemtype

Signed-off-by: Thierry Bugier <tbugier@teclib.com>

Author: btry

inc/field/glpiselectfield.class.php

@@ -221,7 +221,7 @@ public function getAvailableValues(): array {
 
    public function equals($value): bool {
       $value = html_entity_decode($value);
-      $itemtype = $this->question->fields['values'];
+      $itemtype = $this->getSubItemtypeForValues($this->question->fields['values']);
       $item = new $itemtype();
       if ($item->isNewId($this->value)) {
          return ($value === '');
@@ -238,7 +238,7 @@ public function notEquals($value): bool {
 
    public function greaterThan($value): bool {
       $value = html_entity_decode($value);
-      $itemtype = $this->question->fields['values'];
+      $itemtype = $this->getSubItemtypeForValues($this->question->fields['values']);
       $item = new $itemtype();
       if (!$item->getFromDB($this->value)) {
          throw new ComparisonException('Item not found for comparison');