### 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.log.info("DAG %s is missing and will be deactivated.", dag.dag_id)
                    to_deactivate.add(dag.dag_id)
            if to_deactivate:
                deactivated = (
                    session.query(DagModel)
                    .filter(DagModel.dag_id.in_(to_deactivate))
                    .update({DagModel.is_active: False}, synchronize_session="fetch")
                )
                if deactivated:
                    self.log.info("Deactivated %i DAGs which are no longer present in file.", deactivated)
                for dag_id in to_deactivate:
                    SerializedDagModel.remove_dag(dag_id)
                    self.log.info("Deleted DAG %s in serialized_dag table", dag_id)
            self.last_deactivate_stale_dags_time = timezone.utcnow()
    def _run_parsing_loop(self):
        
        if self._async_mode:
            poll_time = 0.0
        else:
            poll_time = None
        self._refresh_dag_dir()
        self.prepare_file_path_queue()
        max_callbacks_per_loop = conf.getint("scheduler", "max_callbacks_per_loop")
        if self._async_mode:
            
            
            self.start_new_processes()
        while True:
            loop_start_time = time.monotonic()