### Apache Airflow version

2.4.1

### What happened

When there are large number of dag files, lets say 10K and each takes sometime to parse,  dag_parser doesnt pick any newly created files till all 10k files are finished parsing

`if not self._file_path_queue:
                self.emit_metrics()
                self.prepare_file_path_queue()`

Above logic only adds new files to queue when queue is empty

### What you think should happen instead

Every loop of dag processor should pick new files and add into file for parsing queue

### How to reproduce

_No response_

### Operating System

All

### Versions of Apache Airflow Providers

_No response_

### Deployment

Docker-Compose

### Deployment details

_No response_

### Anything else

_No response_

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

mock_pid.return_value = 1234
        mock_waitable_handle.return_value = 3
        manager = DagFileProcessorManager(
            dag_directory="directory",
            max_runs=1,
            processor_timeout=timedelta(seconds=5),
            signal_conn=MagicMock(),
            dag_ids=[],
            pickle_dags=False,
            async_mode=True,
        )
        processor = DagFileProcessorProcess(
            file_path="abc.txt",
            pickle_dags=False,
            dag_ids=[],
            dag_directory=TEST_DAG_FOLDER,
            callback_requests=[],
        )
        processor._start_time = timezone.make_aware(datetime.min)
        manager._processors = {"abc.txt": processor}
        manager.waitables[3] = processor
        initial_waitables = len(manager.waitables)
        manager._kill_timed_out_processors()
        mock_kill.assert_called_once_with()
        assert len(manager._processors) == 0
        assert len(manager.waitables) == initial_waitables - 1
    @mock.patch("airflow.dag_processing.processor.DagFileProcessorProcess.pid", new_callable=PropertyMock)
    @mock.patch("airflow.dag_processing.processor.DagFileProcessorProcess")
    def test_kill_timed_out_processors_no_kill(self, mock_dag_file_processor, mock_pid):