workstation: use env group, no need to list productimg

You can use environment groups in kickstarts with this @^ syntax.
So we don't need to duplicate the environment group here, just
use it. We also don't need to list the productimg package, as
it's in the @workstation-product group which the environment
pulls in.

fedora-workstation-packages.ks

@@ -6,21 +6,9 @@
 -@input-methods
 -@standard
 
-# Make sure to sync any additions / removals done here with
-# workstation-product-environment in comps
-@base-x
-@core
-@fonts
-@guest-desktop-agents
-@hardware-support
+# Most of the heavy work is done in comps
+@^workstation-product-environment
 @libreoffice
-@multimedia
-@networkmanager-submodules
-@printing
-@workstation-product
-
-# Branding for the installer
-fedora-productimg-workstation
 
 # Exclude unwanted packages from @anaconda-tools group
 -gfs2-utils