Deprecate FAI's make-fai-nfsroot.conf

Since FAI v4.0 make-fai-nfsroot.conf is no longer relevant, even in
Debian oldoldstable AKA buster we have FAI v5.8.4, so there's no point
in further supporting this.

Sadly we still need the temporary /etc/grml/fai/nfsroot.conf for FAI's
dirinstall usage:

| fai -C /etc/grml/fai -s file:////etc/grml/fai/config -cDEBIAN_BOOKWORM,GRMLBASE,GRML_SMALL,AMD64 - u grml dirinstall ....

FAI relies on this file, otherwise failing with:

| /etc/grml/fai/nfsroot.conf not found.
| You may want to install the package fai-server

grml-live

@@ -221,7 +221,6 @@ bailout() {
 
   # get rid of automatically generated conffiles
   rm -f ${GRML_FAI_CONFIG}/nfsroot.conf
-  rm -f ${GRML_FAI_CONFIG}/make-fai-nfsroot.conf
 
   if [ -n "$CHOWN_USER" ]; then
     log "Setting ownership"
@@ -715,22 +714,11 @@ if [ -z "$FAI_DEBOOTSTRAP_OPTS" ] ; then
   FAI_DEBOOTSTRAP_OPTS="--exclude=info,tasksel,tasksel-data,isc-dhcp-client,isc-dhcp-common --include=aptitude --arch $ARCH"
 fi
 
-# create backup of old (not yet automatically generated) config file
-if [ -f "${GRML_FAI_CONFIG}/make-fai-nfsroot.conf" ] ; then
-  if ! grep -q 'This is an automatically generated file by grml-live' "${GRML_FAI_CONFIG}/make-fai-nfsroot.conf" ; then
-    ewarn "Found old ${GRML_FAI_CONFIG}/make-fai-nfsroot.conf - moving to ${GRML_FAI_CONFIG}/make-fai-nfsroot.conf.outdated"
-    mv "${GRML_FAI_CONFIG}/make-fai-nfsroot.conf" "${GRML_FAI_CONFIG}/make-fai-nfsroot.conf.outdated"
-    eend $?
-  fi
-fi
-
 echo "# This is an automatically generated file by grml-live.
 # Do NOT edit this file, your changes will be lost.
 FAI_DEBOOTSTRAP=\"$FAI_DEBOOTSTRAP\"
 FAI_DEBOOTSTRAP_OPTS=\"$FAI_DEBOOTSTRAP_OPTS\"
 # EOF " > "${GRML_FAI_CONFIG}/nfsroot.conf"
-# support FAI <=3.4.8, versions >=4.0 use nfsroot.conf
-( cd ${GRML_FAI_CONFIG} && ln -sf nfsroot.conf make-fai-nfsroot.conf )
 # }}}
 
 # CHROOT_OUTPUT - execute FAI {{{