### 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)

"""
        Kill all child processes on exit since we don't want to leave
        them as orphaned.
        """
        pids_to_kill = self.get_all_pids()
        if pids_to_kill:
            kill_child_processes_by_pids(pids_to_kill)
    def emit_metrics(self):
        """
        Emit metrics about dag parsing summary
        This is called once every time around the parsing "loop" - i.e. after
        all files have been parsed.
        """
        parse_time = time.perf_counter() - self._parsing_start_time
        Stats.gauge("dag_processing.total_parse_time", parse_time)
        Stats.gauge("dagbag_size", sum(stat.num_dags for stat in self._file_stats.values()))
        Stats.gauge(
            "dag_processing.import_errors", sum(stat.import_errors for stat in self._file_stats.values())
        )
    @property
    def file_paths(self):
        return self._file_paths