### 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)

"""Collect the result from any finished DAG processors"""
        ready = multiprocessing.connection.wait(
            self.waitables.keys() - [self._direct_scheduler_conn], timeout=0
        )
        for sentinel in ready:
            if sentinel is self._direct_scheduler_conn:
                continue
            processor = cast(DagFileProcessorProcess, self.waitables[sentinel])
            self.waitables.pop(processor.waitable_handle)
            self._processors.pop(processor.file_path)
            self._collect_results_from_processor(processor)
        self.log.debug("%s/%s DAG parsing processes running", len(self._processors), self._parallelism)
        self.log.debug("%s file paths queued for processing", len(self._file_path_queue))
    @staticmethod
    def _create_process(file_path, pickle_dags, dag_ids, dag_directory, callback_requests):
        """Creates DagFileProcessorProcess instance."""
        return DagFileProcessorProcess(
            file_path=file_path,
            pickle_dags=pickle_dags,
            dag_ids=dag_ids,
            dag_directory=dag_directory,
            callback_requests=callback_requests,
        )
    def start_new_processes(self):