packaging: Use dh-sysuser

We can drop adding the group manually. We move the udev triggering
to the end to ensure the group is already there.

Signed-off-by: Guido Günther <agx@sigxcpu.org>

debian/feedbackd.postinst

@@ -17,12 +17,12 @@ set -e
 # for details, see https://www.debian.org/doc/debian-policy/ or
 # the debian-policy package
 
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
 case "$1" in
     configure)
-        if ! getent group feedbackd >/dev/null; then
-            addgroup --quiet --system feedbackd
-        fi
-
         # we ship udev rules, so trigger an update
         udevadm trigger --subsystem-match=leds --subsystem-match=input --action=change || true
     ;;
@@ -37,9 +37,6 @@ case "$1" in
 esac
 
 # dh_installdeb will replace this with shell code automatically
-# generated by other debhelper scripts.
-
-#DEBHELPER#
 
 exit 0