### Apache Airflow version

2.4.2

### What happened

In the scenario where we have 2 dags, 1 dag dependent on the other by having an ExternalTaskMarker on the parent dag pointing to the child dag and we have some number of mapped tasks in the child dag that have been expanded (map_index is not -1). 
If we were to clear the parent dag, the child dag's mapped tasks will NOT be cleared. It will not appear in the "Task instances to be cleared" list

### What you think should happen instead

I believe the behaviour should be having the child dag's mapped tasks cleared when the parent dag is cleared.

### How to reproduce

1. Create a parent dag with an ExternalTaskMarker
2. Create a child dag which has some ExternalTaskSensor that the ExternalTaskMarker is pointing to
3. Add any number of mapped tasks downstream of that ExternalTaskSensor
4. Clear the parent dag's ExternalTaskMarker (or any task upstream of it)

### Operating System

Mac OS Monterey 12.6

### Versions of Apache Airflow Providers

_No response_

### Deployment

Official Apache Airflow Helm Chart

### 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)

"""File location of the importable dag 'file' relative to the configured DAGs folder."""
        path = pathlib.Path(self.fileloc)
        try:
            rel_path = path.relative_to(self._processor_dags_folder or settings.DAGS_FOLDER)
            if rel_path == pathlib.Path("."):
                return path
            else:
                return rel_path
        except ValueError:
            
            return path
    @property
    def folder(self) -> str:
        """Folder location of where the DAG object is instantiated."""
        return os.path.dirname(self.fileloc)
    @property
    def owner(self) -> str:
        """
        Return list of all owners found in DAG tasks.
        :return: Comma separated list of owners in DAG tasks
        """
        return ", ".join({t.owner for t in self.tasks})
    @property
    def allow_future_exec_dates(self) -> bool: