bug#44334: 28.0.50; [eldoc] Impossible to avoid creating the *eldoc for xxx* buffer

[Xu Chunyang]

With eldoc-mode, a buffer like *eldoc for setq* is created and updated
all the time, is it possible to stop it? since I don't need the
buffer at all. If the buffer must be created, maybe make it uninteresting by
prefixing the buffer name with a space.

I've tried the following which does not work.

(remove-hook 'eldoc-display-functions #'eldoc-display-in-buffer)

In GNU Emacs 28.0.50 (build 2, x86_64-apple-darwin19.6.0, NS
appkit-1894.60 Version 10.15.7 (Build 19H2))
 of 2020-10-30 built on mac.lan
Repository revision: 3e63213a1fef16ffe38a5024a83d8782e98aabe1
Repository branch: master
Windowing system distributor 'Apple', version 10.3.1894
System Description:  Mac OS X 10.15.7