### 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.
"""Check ``schedule_interval`` and ``timetable`` match.
        This is done as a part of the DAG validation done before it's bagged, to
        guard against the DAG's ``timetable`` (or ``schedule_interval``) from
        being changed after it's created, e.g.
        .. code-block:: python
            dag1 = DAG("d1", timetable=MyTimetable())
            dag1.schedule_interval = "@once"
            dag2 = DAG("d2", schedule="@once")
            dag2.timetable = MyTimetable()
        Validation is done by creating a timetable and check its summary matches
        ``schedule_interval``. The logic is not bullet-proof, especially if a
        custom timetable does not provide a useful ``summary``. But this is the
        best we can do.
        """
        if self.schedule_interval == self.timetable.summary:
            return True
        try:
            timetable = create_timetable(self.schedule_interval, self.timezone)
        except ValueError:
            return False
        return timetable.summary == self.timetable.summary
    def validate(self):