[packagechooser] Remove bogus images

- KDE and GNOME selection images were drawn by me for the bogus
   package model, and should not be used.
 - Keep Calamares logo though, even if it doesn't make much sense
   to use it in package selection.
 - Keep the no-selection image since it might be used more often,
   but it's not very good.

src/modules/packagechooser/packagechooser.qrc

@@ -1,8 +1,6 @@
 <RCC>
     <qresource prefix="/">
         <file>images/no-selection.png</file>
-        <file>images/kde.png</file>
-        <file>images/gnome.png</file>
         <file>images/calamares.png</file>
     </qresource>
 </RCC>