change test to slider for disk create

app/UI/Disk/Forms/UpdateForm.php

@@ -59,9 +59,9 @@ class UpdateForm extends BaseForm implements ClientArea
         $hdd = $vm->getHardDiskRepostiory()->findById($this->id);
         $size = $hdd->getGb();
         $this->resourceManager = new ResourceManager();
-        $field = new Range('additionalDiskSize', $size, $this->resourceManager->disk()->free());
+        $field = new Range('additionalDiskSize', 20, $this->resourceManager->disk()->free());
         $field->addValidator(new DiskSizeValidator('additionalDiskSize',true));
-        $field->setDefaultValue($size);
+        $field->setDefaultValue(20);
         $this->addField($field);
         /**
          * @todo $resourceManager->disk()->free() + current disk size