Bug 17835: Do not reselect translated_description if comes from search_with_localization

Bug 17835: Do not reselect translated_description if comes from search_with_localization

If the Koha::ItemType object has been instanciated from a call to
Koha::ItemTypes->search_with_localization, we already have the
translated_description value. So there is no need to fetch it again from
the DB. This is what this trick does: if the translated_description
column exist in the DBIx::Class result source's column list, that means
the value has already been retrieved.

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Lari Taskula <lari.taskula@jns.fi>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>