Bug 38085: Pick multiple_sortable options for translation

Bug 38085: Pick multiple_sortable options for translation

Bug 29948 added a "multiple_sortable" type for sysprefs, to have the
options sortable. But the options were not picked for translation.

This patch fixes it.

Test plan:
Run `cd misc/translator && perl translate update LANG` before and after
this patch. Notice that with this patch you see the different options of
OPACAuthorIdentifiersAndInformation in the LANG-pref.po file (eg.
"Associated group (373$a$s$t$u$v$0)")
Translate the options
Install the translated version of the templates and confirm that the
strings appear translated on the interface.

Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>