Remove configuration transition code

Was needed in the upgrade to bullseye only.

debian/softflowd.preinst

@@ -1,36 +0,0 @@
-#!/bin/sh
-
-set -e
-
-DEFAULT_CONF='/etc/softflowd/default.conf'
-LEGACY_CONF='/etc/default/softflowd'
-
-case "$1" in
-install)
-    ;;
-upgrade)
-    if \
-        dpkg --compare-versions "$2" lt 0.9.9-4~ &&
-        [ -f "$LEGACY_CONF" ] &&
-        [ ! -f "$DEFAULT_CONF" ] &&
-        [ $(md5sum "$LEGACY_CONF" | awk '{print $1}') != '617dbe97c274b4491b22b85b28f3ccf0' ]
-    then
-        # create /etc/softflowd/default.conf from /etc/default/softflowd
-        # lower-case key names
-        mkdir -p "$(dirname "$DEFAULT_CONF")"
-        sed  -e '
-            s/^INTERFACE=/interface=/ ;
-            s/^OPTIONS=/options=/ ;
-        ' <"$LEGACY_CONF" >"$DEFAULT_CONF"
-    fi
-    ;;
-abort-upgrade)
-    ;;
-*)
-    echo "preinst called with unknown argument '$1'"
-    exit 1
-    ;;
-esac
-
-#DEBHELPER#
-exit 0