### 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)

"""
        Test that when a processor already exist with a filepath, a new processor won't be created
        with that filepath. The filepath will just be removed from the list.
        """
        manager = DagFileProcessorManager(
            dag_directory="directory",
            max_runs=1,
            processor_timeout=timedelta(days=365),
            signal_conn=MagicMock(),
            dag_ids=[],
            pickle_dags=False,
            async_mode=True,
        )
        file_1 = "file_1.py"
        file_2 = "file_2.py"
        file_3 = "file_3.py"
        manager._file_path_queue = [file_1, file_2, file_3]
        
        manager._processors[file_1] = MagicMock()
        
        manager.start_new_processes()
        
        
        
        
        
        assert file_1 in manager._processors.keys()
        assert file_2 in manager._processors.keys()
        assert [file_3] == manager._file_path_queue
    def test_set_file_paths_when_processor_file_path_not_in_new_file_paths(self):