### 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)

mapped.render_template_fields(context=mapped_ti.get_template_context(session=session))
    assert isinstance(mapped_ti.task, MyOperator)
    assert mapped_ti.task.value == "{{ ds }}", "Should not be templated!"
    assert mapped_ti.task.arg1 == "{{ ds }}", "Should not be templated!"
    assert mapped_ti.task.arg2 == "a"
def test_mapped_render_nested_template_fields(dag_maker, session):
    with dag_maker(session=session):
        MockOperatorWithNestedFields.partial(
            task_id="t", arg2=NestedFields(field_1="{{ ti.task_id }}", field_2="value_2")
        ).expand(arg1=["{{ ti.task_id }}", ["s", "{{ ti.task_id }}"]])
    dr = dag_maker.create_dagrun()
    decision = dr.task_instance_scheduling_decisions()
    tis = {(ti.task_id, ti.map_index): ti for ti in decision.schedulable_tis}
    assert len(tis) == 2
    ti = tis[("t", 0)]
    ti.run(session=session)
    assert ti.task.arg1 == "t"
    assert ti.task.arg2.field_1 == "t"
    assert ti.task.arg2.field_2 == "value_2"
    ti = tis[("t", 1)]
    ti.run(session=session)
    assert ti.task.arg1 == ["s", "t"]
    assert ti.task.arg2.field_1 == "t"
    assert ti.task.arg2.field_2 == "value_2"
@pytest.mark.parametrize(
    ["num_existing_tis", "expected"],
    (
        pytest.param(0, [(0, None), (1, None), (2, None)], id="only-unmapped-ti-exists"),
        pytest.param(
            3,