backup.pl: removes any references to ALIENVAULT & SPAMHAUSEDROP from restores

backup.pl: removes any references to ALIENVAULT & SPAMHAUSEDROP from restores

- This patch ensures that if a restore is carried out from an earlier version that includes
   ALIENVAULT and/or SPAMHAUS_EDROP that the references will be removed.
- This is the same code as was put into the update.sh file with the previous patch of this
   set.

Tested-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>