Bug 32110: Fixup to db_rev for non-english, multilingual Koha

Bug 32110: Fixup to db_rev for non-english, multilingual Koha

Without this patch, the update process duplicates all the news and
content entries when they were non-english to start with.

This patch keeps the same process, but new "default" "parent" entries are empty so there'
no duplication in the OPAC display, while still being editable/deletable
in the intranet.

We came through that through many iterations.  This was the least
invasive while still providing satisfying results.

Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>