### 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)

"""
        :param file_path: the path to the file that was processed
        :return: the finish time of the process of the last run, or None if the
            file was never processed.
        """
        stat = self._file_stats.get(file_path)
        return stat.last_finish_time if stat else None
    def get_start_time(self, file_path) -> datetime | None:
        """
        :param file_path: the path to the file that's being processed
        :return: the start time of the process that's processing the
            specified file or None if the file is not currently being processed
        """
        if file_path in self._processors:
            return self._processors[file_path].start_time
        return None
    def get_run_count(self, file_path) -> int:
        """
        :param file_path: the path to the file that's being processed
        :return: the number of times the given file has been parsed
        """
        stat = self._file_stats.get(file_path)
        return stat.run_count if stat else 0
    def get_dag_directory(self) -> str: