Don't include tablespace assignments in the backup dump

This is a comprimise, as this won't help restoring the backup in situations
you want tablespaces, but I'm currently viewing tablespaces as a deployment
concern, so maybe the right thing to do is exclude them. This approach will at
least keep the same behaviour in terms of restoring the backups locally.

This will fix the small dump creation process on data.guix.gnu.org, which is
currently broken because of the tablespace assignments when trying to restore
the backups.

scripts/guix-data-service-backup-database

@@ -17,6 +17,7 @@ ionice -p $$ -c 3 || true
 
 pg_dump --format=custom --compress=9 --serializable-deferrable \
         --no-comments \
+        --no-tablespaces \
         --username=guix_data_service \
         --file="$TEMPORARY_FILE_NAME" \
         "$DATABASE_NAME"