DatePicker Format Not Respected on macOS

### Description

On macOS, the DatePicker control does not respect the Format property. Even when setting a custom format such as Format="dd/MM/yyyy" or Format="MM/dd/yyyy", the control continues to display the date using the system default format.

On other platforms such as Android, iOS, and Windows, the custom format is applied correctly and works as expected.

### Steps to Reproduce

1. [DatePickerFormatBug.zip](https://github.com/user-attachments/files/19832311/DatePickerFormatBug.zip) Run the attached sample on mac platform

### Link to public reproduction project repository

_No response_

### Version with bug

9.0.60 SR6

### Is this a regression from previous behavior?

No, this is something new

### Last version that worked well

Unknown/Other

### Affected platforms

macOS

### Affected platform versions

Mac 15.1

### Did you find any workaround?

_No response_

### Relevant log output

```shell

```

Start by running the attached DatePickerFormatBug.zip sample on macOS 15.1 and compare the DatePicker behavior with Android, iOS, or Windows. Trace the macOS DatePicker implementation and its Format handling. Done means custom formats such as dd/MM/yyyy and MM/dd/yyyy are displayed on macOS as they are on the other platforms.

Written by the indexing model from the issue text.