bug#30883: 27.0.50; completions-annotations face should not be based on italic by default

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Date: Tue, 20 Mar 2018 17:16:37 +0100
> 
> When using insert-char interactively to insert т (CYRILLIC SMALL
> LETTER TE), the completions buffer uses the completions-annotations
> face to display the character after the full unicode name. т is one of
> those characters for which the italic glyph is very different from the
> non-italic one (it actually looks like an 'm'), which is highly
> misleading for the user.

I guess it depends on the default font, because on my system the
italic glyph looks very reasonably similar to the roman variant.

> The easy solution would be to just base the completions-annotations
> face on the default face, but Iʼm sure thereʼs a historical reason for
> its existence.

FWIW, I happen to like the typeface we use there, so I think we should
go to a more boring display only if we have a very good reason.

Thanks.