### 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)

"""This method is deprecated in favor of partial_subset"""
        warnings.warn(
            "This method is deprecated and will be removed in a future version. Please use partial_subset",
            RemovedInAirflow3Warning,
            stacklevel=2,
        )
        return self.partial_subset(*args, **kwargs)
    def partial_subset(
        self,
        task_ids_or_regex: str | re.Pattern | Iterable[str],
        include_downstream=False,
        include_upstream=True,
        include_direct_upstream=False,
    ):
        """
        Returns a subset of the current dag as a deep copy of the current dag
        based on a regex that should match one or many tasks, and includes
        upstream and downstream neighbours based on the flag passed.
        :param task_ids_or_regex: Either a list of task_ids, or a regex to
            match against task ids (as a string, or compiled regex pattern).
        :param include_downstream: Include all downstream tasks of matched
            tasks, in addition to matched tasks.