The toolStripCombobox item's border does not render correctly for MenuStrip/ToolStrip contorl in NET11 mode

### .NET version

.NET 11.0.100-preview.7.26365.114 + Private dlls built from Net11/Integration-3 branch of https://github.com/KlausLoeffelmann/winforms repo

### Did it work in .NET Framework?

Not tested/verified

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

Not support, new feature of https://github.com/dotnet/winforms/pull/14768

### Issue description

The toolStripCombobox item's border is not render well for MenuStrip/ToolStrip contorl in NET11 mode

### Steps to reproduce

1. Create a WinForms application targeting .NET 11
2. Set VisualStylesMode = VisualStylesMode.Net11
3. Add a MenuStrip/ToolStrip control on the Form1.cs[Design] page
4. Add toolStripCombobox item for the menuStrip1/toolStrip1