bug#64089: 30.0.50; `ldap-search' errors out with `wrong-type-argument listp' when called WITHDN == t

[Filipp Gunbin]

Thanks, but the problem is that

- the code before the fix prepended dn as string (and it's not totally broken - 
you can skip attribute translation via var/defcustom, in which case the error 
should not be triggered)
- the fix on emacs-29 now prepends it as cons cell
- my change on master will again use string form

So I'd prefer that we leave that unfixed on emacs-29 instead of creating this 
mess.. Or correct cons cell -> string, if it's worth the trouble.