### 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)

self._direct_scheduler_conn = signal_conn
        self._pickle_dags = pickle_dags
        self._dag_ids = dag_ids
        self._async_mode = async_mode
        self._parsing_start_time: int | None = None
        self._dag_directory = dag_directory
        
        
        
        #
        
        
        if self._async_mode and self._direct_scheduler_conn is not None:
            os.set_blocking(self._direct_scheduler_conn.fileno(), False)
        self.standalone_dag_processor = conf.getboolean("scheduler", "standalone_dag_processor")
        self._parallelism = conf.getint("scheduler", "parsing_processes")
        if (
            conf.get_mandatory_value("database", "sql_alchemy_conn").startswith("sqlite")
            and self._parallelism > 1
        ):
            self.log.warning(
                "Because we cannot use more than 1 thread (parsing_processes = "
                "%d) when using sqlite. So we set parallelism to 1.",
                self._parallelism,
            )
            self._parallelism = 1
        
        self._file_process_interval = conf.getint("scheduler", "min_file_process_interval")