### 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)

manager._add_callback_to_queue(dag2_req1)
        
        assert manager._file_path_queue == [dag2_req1.full_filepath, dag1_req1.full_filepath]
        assert set(manager._callback_to_execute.keys()) == {dag1_req1.full_filepath, dag2_req1.full_filepath}
        assert manager._callback_to_execute[dag1_req1.full_filepath] == [dag1_req1, dag1_sla1]
        assert manager._callback_to_execute[dag2_req1.full_filepath] == [dag2_req1]
        
        manager._add_callback_to_queue(dag1_sla2)
        
        assert manager._file_path_queue == [dag2_req1.full_filepath, dag1_req1.full_filepath]
        assert manager._callback_to_execute[dag1_req1.full_filepath] == [dag1_req1, dag1_sla1]
        
        manager._add_callback_to_queue(dag1_req2)
        
        assert manager._file_path_queue == [dag1_req1.full_filepath, dag2_req1.full_filepath]
        assert manager._callback_to_execute[dag1_req1.full_filepath] == [dag1_req1, dag1_sla1, dag1_req2]
class TestDagFileProcessorAgent:
    def setup_method(self):
        
        self.old_modules = dict(sys.modules)
    def teardown_method(self):
        
        
        remove_list = []
        for mod in sys.modules:
            if mod not in self.old_modules:
                remove_list.append(mod)
        for mod in remove_list:
            del sys.modules[mod]
    def test_reload_module(self):