### 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)

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from airflow.models.abstractoperator import AbstractOperator
from airflow.models.base import Base, StringID
from airflow.models.dagcode import DagCode
from airflow.models.dagpickle import DagPickle
from airflow.models.dagrun import DagRun
from airflow.models.dataset import DagScheduleDatasetReference, DatasetDagRunQueue as DDRQ, DatasetModel
from airflow.models.operator import Operator
from airflow.models.param import DagParam, ParamsDict
from airflow.models.taskinstance import Context, TaskInstance, TaskInstanceKey, clear_task_instances
from airflow.secrets.local_filesystem import LocalFilesystemBackend
from airflow.security import permissions
from airflow.stats import Stats
from airflow.timetables.base import DagRunInfo, DataInterval, TimeRestriction, Timetable
from airflow.timetables.interval import CronDataIntervalTimetable, DeltaDataIntervalTimetable
from airflow.timetables.simple import DatasetTriggeredTimetable, NullTimetable, OnceTimetable
from airflow.typing_compat import Literal
from airflow.utils import timezone
from airflow.utils.dag_cycle_tester import check_cycle
from airflow.utils.dates import cron_presets, date_range as utils_date_range
from airflow.utils.file import correct_maybe_zipped
from airflow.utils.helpers import at_most_one, exactly_one, validate_key
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.session import NEW_SESSION, provide_session
from airflow.utils.sqlalchemy import Interval, UtcDateTime, skip_locked, tuple_in_condition, with_row_locks
from airflow.utils.state import DagRunState, State, TaskInstanceState
from airflow.utils.types import NOTSET, ArgNotSet, DagRunType, EdgeInfoType
if TYPE_CHECKING:
    from types import ModuleType