Disable the network process on Windows

As a result of investigations for #41489, we think that we should disable the network process on Windows.

It is already off for HTTP and turning it on doesn't work currently. It might be better turning the network process off explicitly, and in case remove the pref, if the issues with mingw are solved.

Current status is that HTML is loaded correctly, but it isn't rendered (you can see <title> in the tab, but the page stays blank, and if you interrupt the loading in some way, the user agent style is used).

Screenshots