Bug 33335: (QA follow-up) Polishing and comments

Just send the codes and descriptions only to client.
Adding a few comments to the reduce construction.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

admin/marc-overlay-rules.pl

@@ -133,7 +133,7 @@ elsif ($op eq 'doedit' || $op eq 'add') {
 }
 
 my $categories = Koha::Patron::Categories->search_with_library_limits( {},
-    { order_by => ['description'] } )->unblessed;
+    { order_by => ['description'], columns => [ 'categorycode', 'description' ] } )->unblessed;
 
 $template->param(
     rules      => $rules,

koha-tmpl/intranet-tmpl/prog/en/modules/admin/marc-overlay-rules.tt

@@ -456,6 +456,8 @@
         });
 
         var categories = [% To.json( categories ) | $raw %];
+        // Add * => * to this array of objects, and *reduce* it to one object
+        // Note: This allows displaying a sorted list of categories later, but we still depend on an object!
         categories.unshift({ categorycode: '*', description: '*'});
         categories = categories.reduce( ( a,c ) => ( { ...a, [c.categorycode]: c.description } ), {} );