### 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)

processor = self.waitables.get(sentinel)
                if not processor:
                    continue
                self._collect_results_from_processor(processor)
                self.waitables.pop(sentinel)
                self._processors.pop(processor.file_path)
            if self.standalone_dag_processor:
                self._fetch_callbacks(max_callbacks_per_loop)
            self._deactivate_stale_dags()
            DagWarning.purge_inactive_dag_warnings()
            self._refresh_dag_dir()
            self._kill_timed_out_processors()
            
            
            if not self._file_path_queue:
                self.emit_metrics()
                self.prepare_file_path_queue()
            self.start_new_processes()
            
            self._num_run += 1
            if not self._async_mode:
                self.log.debug("Waiting for processors to finish since we're using sqlite")
                
                
                
                
                self.wait_until_finished()
            
            self.collect_results()
            self._print_stat()