change test to slider for disk create

app/UI/Disk/Forms/UpdateForm.php

@@ -43,8 +43,11 @@ class UpdateForm extends BaseForm implements ClientArea
         $this->setProvider(new DiskProvider());
         $this->initFields();
         $this->loadDataToForm();
-        $this->getField('additionalDiskSize')['minValue']->setValue(20);
-
+        $rangeField = $this->getField('additionalDiskSize');
+        $rangeField['minValue'] = parent::getFormData()['size'];
+        $rangeField['defaultValue'] = parent::getFormData()['size'];
+        $this->reloadForm();
+        
         logModuleCall(
             'proxmoxCloud',
             __FUNCTION__,