### Apache Airflow version

2.4.2

### What happened

Create a DAG and set the schedule parameter using a CronTriggerTimeTable instance. Enable the DAG so that there is DAG run data. Try to access the Calendar View for the DAG. An ERR_EMPTY_RESPONSE error is displayed instead of the page.

The Calendar View is accessible for other DAGs  that are using the schedule_interval set to a cron string instead.

### What you think should happen instead

The Calendar View should have been displayed.

### How to reproduce

Create a DAG and set the schedule parameter to a CronTriggerTimeTable instance. Enable the DAG and allow some DAG runs to occur. Try to access the Calender View for the DAG.

### Operating System

Red Hat Enterprise Linux 8.6

### Versions of Apache Airflow Providers

_No response_

### Deployment

Virtualenv installation

### Deployment details

Airflow 2.4.2 installed via pip with Python3.9 to venv using constraints.

### 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)

"""
        An endpoint helping check the health status of the Airflow instance,
        including metadatabase and scheduler.
        """
        payload = {"metadatabase": {"status": "unhealthy"}}
        latest_scheduler_heartbeat = None
        scheduler_status = "unhealthy"
        payload["metadatabase"] = {"status": "healthy"}
        try:
            scheduler_job = SchedulerJob.most_recent_job()
            if scheduler_job:
                latest_scheduler_heartbeat = scheduler_job.latest_heartbeat.isoformat()
                if scheduler_job.is_alive():
                    scheduler_status = "healthy"
        except Exception:
            payload["metadatabase"]["status"] = "unhealthy"
        payload["scheduler"] = {
            "status": scheduler_status,
            "latest_scheduler_heartbeat": latest_scheduler_heartbeat,
        }
        return flask.json.jsonify(payload)
    @expose("/home")
    @auth.has_access(
        [
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_WEBSITE),
        ]
    )
    def index(self):