### 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)

extra.update(json.loads(extra_json))
            except (JSONDecodeError, TypeError):
                flash(
                    Markup(
                        "<p>The <em>Extra</em> connection field contained an invalid value for Conn ID: "
                        "<q>{conn_id}</q>.</p>"
                        "<p>If connection parameters need to be added to <em>Extra</em>, "
                        "please make sure they are in the form of a single, valid JSON object.</p><br>"
                        "The following <em>Extra</em> parameters were <b>not</b> added to the connection:<br>"
                        "{extra_json}"
                    ).format(conn_id=conn_id, extra_json=extra_json),
                    category="error",
                )
                del form.extra
        del extra_json
        for key in self.extra_fields:
            if key in form.data and key.startswith("extra__"):
                
                
                conn_type_from_extra_field = key.split("__")[1]
                if conn_type_from_extra_field == conn_type:
                    value = form.data[key]
                    
                    
                    if value != "":
                        field_name = self.extra_field_name_mapping[key]
                        extra[field_name] = value
        if extra.keys():
            form.extra.data = json.dumps(extra)
    def prefill_form(self, form, pk):