Remove the Installing DesktopServer doc article

[lukecav]

Issue Description

ServerPress the company behind DesktopServer has shut down and it is no longer possible to download the DesktopServer application.
https://wptavern.com/serverpress-is-shutting-down

URL of the Page with the Issue

https://make.wordpress.org/core/handbook/tutorials/installing-a-local-server/desktopserver/

Section of Page with the issue

https://make.wordpress.org/core/handbook/tutorials/installing-a-local-server/desktopserver/
https://make.wordpress.org/core/handbook/tutorials/installing-a-local-server/desktopserver/#1-downloading-desktopserver

Why is this a problem?

ServerPress has shut down, and it is no longer possible to download the DesktopServer application.
https://serverpress.com/downloads/

Suggested Fix

To remove the DesktopServer doc.

[sabernhardt]

#522 is about the same handbook page, and that report was moved to Core Trac:
https://core.trac.wordpress.org/ticket/56878