Bug 32818: Fix cataloguing/value_builder/marc21_field_005.pl

Remove unnecessary return statement

This is part of the refactoring happening in bug 30975

Test plan:
1. Verify that the plugin continues to work as before

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

cataloguing/value_builder/marc21_field_005.pl

@@ -34,7 +34,6 @@ my $builder = sub {
 
 function Focus$function_name(event) {
     document.getElementById(event.data.id).value='$date';
-    return 0;
 }
 
 </script>