In .NET 9 Preview 6, serialization of style using XamlWriter and XamlReader throws exception

### Description

In .NET 9 Preview 6, serialization and deserialization of style using XamlWriter and XamlReader throws exception. But in .NET 8 and other framework versions, it works fine. Please find the code below.

In .NET 9 Preview 6, most of the setter tags do not have tags in the output file which results in the exception.

```
public string filePath = "style.xml";

StringWriter stringWriter = new StringWriter();

// for saving
Style style = new Style(typeof(System.Windows.Shapes.Path));
style.Setters.Add(new Setter(System.Windows.Shapes.Path.StretchProperty, Stretch.Fill));
style.Setters.Add(new Setter(System.Windows.Shapes.Path.FillProperty, Brushes.Black));

System.Windows.Markup.XamlWriter.Save(style, stringWriter);

File.WriteAllText(filePath, stringWriter.ToString());

// for loading

string xamlContent = File.ReadAllText(filePath);

// Parse the XAML content back into a Style object
using (StringReader stringReader = new StringReader(xamlContent))
{
using (XmlReader xmlReader = XmlReader.Create(stringReader))
{
Style loadedStyle = (Style)XamlReader.Load(xmlReader);
}
}
```

### Reproduction Steps

Use the above codes to replicate the issue.

### Expected behavior

Like other Net Frameworks and Core versions, the XAMLWriter should create the tag for the Fill property.

### Actual behavior

the XAMLWriter has not created the tag for the Fill property.

### Regression?

_No response_

### Known Workarounds

_No response_

### Configuration

Net 9 Preview 6

### Other information

_No response_