### 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)

all_files_processed = all(self.get_last_finish_time(x) is not None for x in self.file_paths)
            max_runs_reached = self.max_runs_reached()
            try:
                if self._direct_scheduler_conn:
                    self._direct_scheduler_conn.send(
                        DagParsingStat(
                            max_runs_reached,
                            all_files_processed,
                        )
                    )
            except BlockingIOError:
                
                
                
                
                
                self.log.debug("BlockingIOError received trying to send DagParsingStat, ignoring")
            if max_runs_reached:
                self.log.info(
                    "Exiting dag parsing loop as all files have been processed %s times", self._max_runs
                )
                break
            if self._async_mode:
                loop_duration = time.monotonic() - loop_start_time
                if loop_duration < 1:
                    poll_time = 1 - loop_duration
                else:
                    poll_time = 0.0
    @provide_session
    def _fetch_callbacks(self, max_callbacks: int, session: Session = NEW_SESSION):