Bug 15940 - Remove unused JavaScript from authorities MARC subfield structure

 Bug 15940 - Remove unused JavaScript from authorities MARC subfield structure

The authorities MARC subfield structure template contains some unused
JavaScript, "function displayMoreConstraint()" This patch removes it.

To test, apply the patch and go to Administration -> Authority types ->
MARC structure -> Subfields -> Edit subfields and confirm that there are
no JavaScript errors and tab switching works correctly.

A search of the source code should show no instances of
"displayMoreConstraint."

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
  No regression, no JS warning.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>