bug#52504: 28.0.90; Ediff control buffer not fully resized

[Eli Zaretskii]

> From: Kevin Fleming <kvnflm@gmail.com>
> Date: Wed, 15 Dec 2021 19:29:05 +0900
> 
> When running ediff in a terminal (reproducible with emacs -Q -nw), or in
> a GUI with (setq ediff-window-setup-function 'ediff-setup-windows-plain),
> pressing the ? key only increases the size of the control buffer's
> window by 2 lines, not enough to display the full help text. Using git
> bisect suggests that this started happening with this commit on the
> emacs-28 branch:
> 
> [f26a027d6b8e0b894d5d28c446643d411b376ea9] Fix ediff3 layouts with 
> window-combination-resize non-nil (Bug#49277)

Martin, could you please take a look?  If this is a regression, I'd
like to have it fixed on the emacs-28 branch.

Thanks.