### Apache Airflow version

2.6.1

### What happened

When playing around with the form features as interoduced in AIP-50 and using the select list option via `enum` I realized that the default value will not be correctly picked when the form is loaded. Instead the first value always will be pre-selected.

### What you think should happen instead

Default value should be respected

### How to reproduce

Modify the `airflow/example_dags/example_params_ui_tutorial.py:68` and change the default to some other value. Load the form and see that `value 1` is still displayed on form load.

### Operating System

Ubuntu 20.04

### Versions of Apache Airflow Providers

not relevant

### Deployment

Official Apache Airflow Helm Chart

### Deployment details

not relevant

### Anything else

Workaround: Make your default currently top of the list.

### 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)

True,
            type="boolean",
            title="Please confirm",
            description="A On/Off selection with a proper description.",
        ),
        
        "date_time": Param(
            f"{datetime.date.today()}T{datetime.time(hour=12, minute=17, second=00)}+00:00",
            type="string",
            format="date-time",
            title="Date-Time Picker",
            description="Please select a date and time, use the button on the left for a pup-up calendar.",
        ),
        "date": Param(
            f"{datetime.date.today()}",
            type="string",
            format="date",
            title="Date Picker",
            description="Please select a date, use the button on the left for a pup-up calendar. "
            "See that here are no times!",
        ),
        "time": Param(
            f"{datetime.time(hour=12, minute=13, second=14)}",
            type=["string", "null"],
            format="time",
            title="Time Picker",
            description="Please select a time, use the button on the left for a pup-up tool.",
        ),