### 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)

def setup_method(self):
        dictConfig(DEFAULT_LOGGING_CONFIG)
        clear_db_runs()
        clear_db_serialized_dags()
        clear_db_dags()
        clear_db_callbacks()
    def teardown_class(self):
        clear_db_runs()
        clear_db_serialized_dags()
        clear_db_dags()
        clear_db_callbacks()
    def run_processor_manager_one_loop(self, manager, parent_pipe):
        if not manager._async_mode:
            parent_pipe.send(DagParsingSignal.AGENT_RUN_ONCE)
        results = []
        while True:
            manager._run_parsing_loop()
            while parent_pipe.poll(timeout=0.01):
                obj = parent_pipe.recv()
                if not isinstance(obj, DagParsingStat):
                    results.append(obj)
                elif obj.done:
                    return results
            raise RuntimeError("Shouldn't get here - nothing to read, but manager not finished!")
    @conf_vars({("core", "load_examples"): "False"})
    def test_remove_file_clears_import_error(self, tmpdir):