Update the debian-edu task definition

Throw away most of the old package list, let's start with a small list
and build up.

tasks/buster/debian-edu

@@ -1,35 +1,3 @@
-ltsp-client-builder
-debian-edu-archive-keyring-udeb
 debian-edu-install-udeb
-debian-edu-profile-udeb
-eatmydata
-etckeeper
-
-exim4-daemon-heavy
-localechooser
-debian-edu-archive-keyring
-atmel-firmware
-firmware-atheros
-firmware-bnx2
-firmware-bnx2x
-firmware-brcm80211
-firmware-intelwimax
-firmware-ipw2x00
-firmware-ivtv
-firmware-iwlwifi
-firmware-linux-nonfree
-firmware-netxen
-firmware-qlogic
-firmware-ralink
-firmware-realtek
-libertas-firmware
-b43-fwcutter
-wireless-tools
-wpasupplicant
-acpi
-mdetect
-xresprobe
-read-edid
-education-tasks
 debian-edu-config
 debian-edu-install