[Dark Mode] MonthCalendar/DateTimePicker is not in drak mode after enabled SystemColorMode.Dark

[Olina-Zhang]

.NET version

9.0.0-rc.1.24418.2 + private dlls built from winforms repo main branch

Did it work in .NET Framework?

No

Did it work in any of the earlier releases of .NET Core or .NET 5+?

This is a new feature Dark Mode: #11857

Issue description

MonthCalendar/DateTimePicker is not in drak mode after enabled SystemColorMode.Dark

Steps to reproduce

1. Create a WinForms .NET application with MonthCalendar/DateTimePicker control
2. Enable DarkMode by Application.SetColorMode(SystemColorMode.Dark) in Program.cs file
3. Run application to observe

[dotnet-policy-service]

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Happy Coding!