Ozone: Adjust determination of platforms for ozone_auto_platforms=true
CL adds an explicit condition for Desktop Linux to ensure that both
Wayland and X11 are enabled on that platform. For unknown platforms
(i.e. other than Cast, Chrome OS or Desktop Linux) for which nothing
can be said about available windowing systems, only headless is enabled.
CL also removes the obsolete comments regarding dependencies and bots.