### 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)

SerializedDagModel.write_dag(dag)
            
            stat = DagFileStat(
                num_dags=1,
                import_errors=0,
                last_finish_time=timezone.utcnow() + timedelta(hours=1),
                last_duration=1,
                run_count=1,
            )
            manager._file_paths = [test_dag_path]
            manager._file_stats[test_dag_path] = stat
            active_dag_count = (
                session.query(func.count(DagModel.dag_id))
                .filter(DagModel.is_active, DagModel.fileloc == test_dag_path)
                .scalar()
            )
            assert active_dag_count == 1
            serialized_dag_count = (
                session.query(func.count(SerializedDagModel.dag_id))
                .filter(SerializedDagModel.fileloc == test_dag_path)
                .scalar()
            )
            assert serialized_dag_count == 1
            manager._deactivate_stale_dags()
            active_dag_count = (
                session.query(func.count(DagModel.dag_id))
                .filter(DagModel.is_active, DagModel.fileloc == test_dag_path)
                .scalar()
            )
            assert active_dag_count == 0