### Body

There are some use cases where users want to trigger new DAG run as soon as one finished. This is a request I've seen several times with some variations (for example like this [Stackoverflow question](https://stackoverflow.com/q/75623153/14624409)) but the basic request is the same.

The workaround users do to get such functionality is place `TriggerDagRunOperator` as last task of their DAG invoking the same DAG:

```
from datetime import datetime

from airflow import DAG
from airflow.operators.empty import EmptyOperator
from airflow.operators.trigger_dagrun import TriggerDagRunOperator

with DAG(
    dag_id="example",
    start_date=datetime(2023, 1, 1,),
    catchup=False,
    schedule=None,
) as dag:
    task = EmptyOperator(task_id="first")
    trigger = TriggerDagRunOperator(
        task_id="trigger",
        trigger_dag_id="example",
    )

    task >> trigger

```

As you can see this works nicely:
![Screenshot 2023-03-03 at 14 20 51](https://user-images.githubusercontent.com/45845474/222718862-dfde8a41-24b6-4991-b318-b7f9784514f6.png)

My suggestion is to add first class support for this use case, so the above example will be changed to:

```

from datetime import datetime

from airflow import DAG
from airflow.operators.empty import EmptyOperator
from airflow.operators.trigger_dagrun import TriggerDagRunOperator

with DAG(
    dag_id="example",
    start_date=datetime(2023, 1, 1,),
    catchup=False,
    schedule="@continues",
) as dag:
    task = EmptyOperator(task_id="first")
```

I guess it won't exactly be `"@continues"` but more likely new [ScheduleArg](https://github.com/apache/airflow/blob/8b8552f5c4111fe0732067d7af06aa5285498a79/airflow/models/dag.py#L127) type but I show it like that just for simplification of the idea.

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
assert hash(dag) == hash(dag)
        assert hash(dag_eq) == hash(dag)
        assert hash(dag_diff_name) != hash(dag)
        assert hash(dag_subclass) != hash(dag)
    def test_get_paused_dag_ids(self):
        dag_id = "test_get_paused_dag_ids"
        dag = DAG(dag_id, is_paused_upon_creation=True)
        dag.sync_to_db()
        assert DagModel.get_dagmodel(dag_id) is not None
        paused_dag_ids = DagModel.get_paused_dag_ids([dag_id])
        assert paused_dag_ids == {dag_id}
        with create_session() as session:
            session.query(DagModel).filter(DagModel.dag_id == dag_id).delete(synchronize_session=False)
    @pytest.mark.parametrize(
        "schedule_interval_arg, expected_timetable, interval_description",
        [
            (None, NullTimetable(), "Never, external triggers only"),
            ("@daily", cron_timetable("0 0 * * *"), "At 00:00"),
            ("@weekly", cron_timetable("0 0 * * 0"), "At 00:00, only on Sunday"),
            ("@monthly", cron_timetable("0 0 1 * *"), "At 00:00, on day 1 of the month"),
            ("@quarterly", cron_timetable("0 0 1 */3 *"), "At 00:00, on day 1 of the month, every 3 months"),
            ("@yearly", cron_timetable("0 0 1 1 *"), "At 00:00, on day 1 of the month, only in January"),
            ("5 0 * 8 *", cron_timetable("5 0 * 8 *"), "At 00:05, only in August"),
            ("@once", OnceTimetable(), "Once, as soon as possible"),
            (datetime.timedelta(days=1), delta_timetable(datetime.timedelta(days=1)), ""),
            ("30 21 * * 5 1", cron_timetable("30 21 * * 5 1"), ""),
        ],
    )
    def test_timetable_and_description_from_schedule_interval_arg(