### 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)

"required_field": Param(
            "You can not trigger if no text is given here!",
            type="string",
            title="Required text field",
            description="This field is required. You can not submit without having text in here.",
        ),
        "optional_field": Param(
            "optional text, you can trigger also w/o text",
            type=["null", "string"],
            title="Optional text field",
            description_html="This field is optional. As field content is JSON schema validated you must "
            "allow the <code>null</code> type.",
        ),
        
        
        
        
        "checked_text": Param(
            "length-checked-field",
            type="string",
            title="Text field with length check",
            description_html="""This field is required. And you need to provide something between 10 and 30
            characters. See the
            <a href='https://json-schema.org/understanding-json-schema/reference/string.html'>
            JSON schema description (string)</a> in for more details""",
            minLength=10,
            maxLength=20,
            section="JSON Schema validation options",
        ),