bug#71479: 30.0.50; describe-key description incorrect when using input methods

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Date: Mon, 10 Jun 2024 18:45:36 +0200
> 
> 
> emacs -Q
> C-u C-\ cyrillic-translit
> C-h k z h
> 
> =>
>     ж (translated from h ж) runs the command
>     self-insert-command (found in global-map), which is an interactive
>     primitive-function in ‘C source code’.
> 
> This should say '*translated from z h)'. The underlying reason is that
> quail.el messes around with `last-command-event', which confuses
> describe-key.
> 
> I doubt this issue is confined to this particular input method.

Right, it looks like the problem is in this-single-command-raw-keys,
and more deeply in what we store in the raw_keybuf vector.

Stefan, any suggestions for how we could fix this?