### Apache Airflow version

main (development)

### What happened

When creating a DAG with Task Groups and a Mapped Operator, if the Task Group is passed as argument to Mapped Operator's `partial` method it is ignored and the operator is not added to the group.

### What you think should happen instead

The Mapped Operator should be added to the Task Group passed as an argument.

### How to reproduce

Create a DAG with a source code like the following one

```python
from airflow import DAG
from airflow.operators.bash import BashOperator
from airflow.operators.empty import EmptyOperator
from airflow.utils import timezone
from airflow.utils.task_group import TaskGroup


with DAG("dag", start_date=timezone.datetime(2016, 1, 1)) as dag:
    start = EmptyOperator(task_id="start")
    finish = EmptyOperator(task_id="finish")

    group = TaskGroup("test-group")
    commands = ["echo a", "echo b", "echo c"]
    mapped = BashOperator.partial(task_id="task_2", task_group=group).expand(bash_command=commands)

    start >> group >> finish

# assert mapped.task_group == group

```

### Operating System

macOS 13.2.1 (22D68)

### Versions of Apache Airflow Providers

_No response_

### Deployment

Other

### 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)

if not dag:
        return {}, ParamsDict()
    dag_args = copy.copy(dag.default_args)
    dag_params = copy.deepcopy(dag.params)
    if task_group:
        if task_group.default_args and not isinstance(task_group.default_args, collections.abc.Mapping):
            raise TypeError("default_args must be a mapping")
        dag_args.update(task_group.default_args)
    return dag_args, dag_params
def get_merged_defaults(
    dag: DAG | None,
    task_group: TaskGroup | None,
    task_params: collections.abc.MutableMapping | None,
    task_default_args: dict | None,
) -> tuple[dict, ParamsDict]:
    args, params = _get_parent_defaults(dag, task_group)
    if task_params:
        if not isinstance(task_params, collections.abc.Mapping):
            raise TypeError("params must be a mapping")
        params.update(task_params)
    if task_default_args:
        if not isinstance(task_default_args, collections.abc.Mapping):
            raise TypeError("default_args must be a mapping")
        args.update(task_default_args)
        with contextlib.suppress(KeyError):
            params.update(task_default_args["params"] or {})
    return args, params
class _PartialDescriptor: