bug#63550: proced-refine-with-update-test is racy

[Eli Zaretskii]

> Cc: Mattias Engdegård <mattias.engdegard@gmail.com>,
>  63550@debbugs.gnu.org
> From: Laurence Warne <laurencewarne@gmail.com>
> Date: Sun, 21 May 2023 09:37:10 +0100
> 
> Strange, I can't seem to reproduce running it continuously (I'm on linux 
> also).  Though whilst looking
> over the test suite, I don't think I like the approach I took.  I've attached 
> a new patch which changes the
> test suite to mock the list of active processes (of course comments welcome).
> 
> Are either of you able to test whether this fixes the test in question?  The 
> change also makes the tests
> a lot faster to run and hopefully less system dependent.

Is mocking out the real Proced display a good idea in this case?
These tests test the ability to manipulate real-life process-attribute
displays, so showing they work in synthetic environment verifies only
part of the functionality, no?