### 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)

"""Returns the dag_director as a string."""
        if isinstance(self._dag_directory, Path):
            return str(self._dag_directory.resolve())
        else:
            return str(self._dag_directory)
    def set_file_paths(self, new_file_paths):
        """
        Update this with a new set of paths to DAG definition files.
        :param new_file_paths: list of paths to DAG definition files
        :return: None
        """
        self._file_paths = new_file_paths
        self._file_path_queue = [x for x in self._file_path_queue if x in new_file_paths]
        
        filtered_processors = {}
        for file_path, processor in self._processors.items():
            if file_path in new_file_paths:
                filtered_processors[file_path] = processor
            else:
                self.log.warning("Stopping processor for %s", file_path)
                Stats.decr("dag_processing.processes")
                processor.terminate()
                self._file_stats.pop(file_path)
        self._processors = filtered_processors
    def wait_until_finished(self):