Fix a random bug in test_move_parent_while_syncing_a_lot_of_files()

self = <tests.old_functional.test_local_move_folders.TestLocalMoveFolders testMethod=test_move_parent_while_syncing_a_lot_of_files>

    def tearDown(self):
        with suppress(TypeError):
>           self.engine_1._local_watcher.localScanFinished.disconnect(
                self.app.local_scan_finished
            )
E           AttributeError: 'TestLocalMoveFolders' object has no attribute 'engine_1'

self       = <tests.old_functional.test_local_move_folders.TestLocalMoveFolders testMethod=test_move_parent_while_syncing_a_lot_of_files>

tests/old_functional/test_local_move_folders.py:62: AttributeError