### 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)

self.print_stats_interval = conf.getint("scheduler", "print_stats_interval")
        
        self._processors: dict[str, DagFileProcessorProcess] = {}
        self._num_run = 0
        
        self._file_stats: dict[str, DagFileStat] = {}
        
        self.last_dag_dir_refresh_time = timezone.make_aware(datetime.fromtimestamp(0))
        
        self.last_stat_print_time = 0
        
        self.last_deactivate_stale_dags_time = timezone.make_aware(datetime.fromtimestamp(0))
        
        self.deactivate_stale_dags_interval = conf.getint("scheduler", "deactivate_stale_dags_interval")
        
        self._processor_timeout = processor_timeout
        
        self.dag_dir_list_interval = conf.getint("scheduler", "dag_dir_list_interval")
        
        self._callback_to_execute: dict[str, list[CallbackRequest]] = defaultdict(list)
        self._log = logging.getLogger("airflow.processor_manager")
        self.waitables: dict[Any, MultiprocessingConnection | DagFileProcessorProcess] = (
            {
                self._direct_scheduler_conn: self._direct_scheduler_conn,
            }
            if self._direct_scheduler_conn is not None
            else {}
        )
    def register_exit_signals(self):