Stop using dh_gnome_clean

This will allow us to simplify the Debian GNOME team packaging to get rid of debian/control.in in most cases, without needing to override dh_gnome_clean or drop dh-sequence-gnome from Build-Depends. dh-sequence-gnome is used by Ubuntu to run dh_translations which is required for Ubuntu language packs.

There are still a few users that would currently fail to build if we just delete the cdbs era uploaders.mk:

gtk+2.0, gtk+3.0, libglade2

so let's defer that removal until later. There are a few different ways to fix it but it will take a little more effort.