Revert "grub2: Exit gracefully if the configuration has BLS enabled"

This reverts commit 985a141002.
It turned out that some people have old bootloaders, and hence
get the "no entries" problem.  That's much, much much worse
than double entries.

src/boot/grub2/grub2-15_ostree

@@ -26,13 +26,6 @@ if ! test -d /ostree/repo; then
     exit 0
 fi
 
-# Gracefully exit if the grub2 configuration has BLS enabled,
-# since there is no need to create menu entries in that case.
-. /etc/default/grub
-if test ${GRUB_ENABLE_BLSCFG} = "true"; then
-    exit 0
-fi
-
 # Make sure we're in the right environment
 if ! test -n "${GRUB_DEVICE}"; then
     echo "This script must be run as a child of grub2-mkconfig" 1>&2