Remove support for Gnome printing from wxGTK.

It was replaced by GTK+ printing several years ago and is almost never used
any longer anyhow, so any problems in this code (and there are some) would
never be found and fixed.

Also update the message catalogs to avoid having the strings not used any
more, as they were only used in Gnome printing code.

Closes #15517.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74912 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775