just need to delete documents, as these methods are only used when closing...

just need to delete documents, as these methods are only used when closing OpenBoard. Fix bad indexes issues

src/document/UBDocumentController.cpp

@@ -2644,7 +2644,7 @@ void UBDocumentController::deleteDocumentsInFolderOlderThan(const QModelIndex &i
         {
             if (documentProxy->lastUpdate() < QDateTime::currentDateTime().addDays(-days))
             {
-                deleteIndexAndAssociatedData(child);
+                UBPersistenceManager::persistenceManager()->deleteDocument(documentProxy);
             }
         }
         else