KFileItemModelRolesUpdater: Avoid refreshing items when we receive their content count

It concerns the detail view.

It can cause multiple preview to be generated for the same file.
This is visible for directories whose icons use a random value for their inner files thumbnails.

Only the view needs to be updated for this model change.

src/kitemviews/kfileitemmodelrolesupdater.cpp

@@ -782,7 +782,11 @@ void KFileItemModelRolesUpdater::slotDirectoryContentsCountReceived(const QStrin
                 data.insert("isExpandable", count > 0);
             }
 
+            disconnect(m_model, &KFileItemModel::itemsChanged,
+                       this,    &KFileItemModelRolesUpdater::slotItemsChanged);
             m_model->setData(index, data);
+            connect(m_model, &KFileItemModel::itemsChanged,
+                       this,    &KFileItemModelRolesUpdater::slotItemsChanged);
         }
     }
 }