### Apache Airflow version

2.4.3, 2.5.0

### What happened

when use output from task decorator as parameter (external_task_ids) in ExternalTaskSensor, it show up this log:

```
Broken DAG: [+++++/airflow/dags/TEST_NEW_PIPELINE.py] Traceback (most recent call last):
  File "+++++/env3.10.5/lib/python3.10/site-packages/airflow/models/baseoperator.py", line 408, in apply_defaults
    result = func(self, **kwargs, default_args=default_args)
  File "+++++/env3.10.5/lib/python3.10/site-packages/airflow/sensors/external_task.py", line 164, in __init__
    if external_task_ids and len(external_task_ids) > len(set(external_task_ids)):
TypeError: object of type 'PlainXComArg' has no len()
```

note: +++++ is just a mask for irrelevant information.

### What you think should happen instead

this document https://airflow.apache.org/docs/apache-airflow/stable/tutorial/taskflow.html
show that we can use it without any warning, note about it.

found relative problem in [https://github.com/apache/airflow/issues/27328](url)
should move all the check in __\_\_init\_\___ into __poke__ method.

### How to reproduce

```
from airflow.decorators import dag, task
from airflow.operators.python import get_current_context

from airflow.sensors.external_task import ExternalTaskSensor
from datetime import datetime

configure = {"dag_id": "test_new_skeleton",
                    "schedule": None,
                    "start_date": datetime(2022,1,1),
}

@task
def preprocess_dependency() -> list:
    return ["random-task-name"]

@dag(**configure)
def pipeline(): 
    t_preprocess = preprocess_dependency()
    task_dependency = ExternalTaskSensor(task_id=f"Check_Dependency",
                                         external_dag_id='random-dag-name-that-exist',
                                         external_task_ids=t_preprocess ,
                                         poke_interval=60,
                                         mode="reschedule",
                                         timeout=172800,
                                         allowed_states=['success'],
                                         failed_states=['failed', 'skipped'],
                                         check_existence=True,)


dag = pipeline()
```


### Operating System

REHL 7

### Versions of Apache Airflow Providers

_No response_

### Deployment

Virtualenv installation

### Deployment details

_No response_

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] 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)

refreshed_dag_info = DagBag(read_dags_from_db=True).get_dag(self.external_dag_id, session)
        task_group = refreshed_dag_info.task_group_dict.get(self.external_task_group_id)
        if task_group:
            return [task.task_id for task in task_group]
        
        
        return [self.external_task_group_id]
    def _handle_execution_date_fn(self, context) -> Any:
        """
        Handle backward compatibility.
        This function is to handle backwards compatibility with how this operator was
        previously where it only passes the execution date, but also allow for the newer
        implementation to pass all context variables as keyword arguments, to allow
        for more sophisticated returns of dates to return.
        """
        from airflow.utils.operator_helpers import make_kwargs_callable
        
        logical_date = context["logical_date"]
        kwargs = {k: v for k, v in context.items() if k not in {"execution_date", "logical_date"}}
        
        
        kwargs["context"] = context
        if TYPE_CHECKING:
            assert self.execution_date_fn is not None
        kwargs_callable = make_kwargs_callable(self.execution_date_fn)
        return kwargs_callable(logical_date, **kwargs)
class ExternalTaskMarker(EmptyOperator):