tedst/utf8: Change default font used under Windows for "Unicode Display Test"

The Windows doc at https://learn.microsoft.com/en-us/typography/font-list/arial-unicode-ms
 of the "Arial Unicode MS" font reads
"The font was included with Office but not Windows. …
We stopped servicing and updating Arial Unicode and no longer install it as part of Office."
Using that font is therefore not the best choice.
This commmit uses "Microsoft Sans Serif" instead available in all Windows versions
since Windows 2000.