### 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)

"""Returns the pipe for sending Callbacks to DagProcessorManager."""
        if not self._parent_signal_conn:
            raise ValueError("Process not started.")
        return self._parent_signal_conn
    def wait_until_finished(self) -> None:
        """Waits until DAG parsing is finished."""
        if not self._parent_signal_conn:
            raise ValueError("Process not started.")
        if self._async_mode:
            raise RuntimeError("wait_until_finished should only be called in sync_mode")
        while self._parent_signal_conn.poll(timeout=None):
            try:
                result = self._parent_signal_conn.recv()
            except EOFError:
                return
            self._process_message(result)
            if isinstance(result, DagParsingStat):
                
                
                return
    @staticmethod
    def _run_processor_manager(