Bug 27706: (bug 24488 follow-up) Fix libraries column filter

Bug 27706: (bug 24488 follow-up) Fix libraries column filter

From commit 2285c2d65752dcc899d3fdcff634e6927a1cbbf0
     Bug 24488: Show correct first patron details on Holds to pull

               $('select', this).change( function () {
-                  var filter_value = $(this).val();
-                  holdst.fnFilter( filter_value, 5, true );
+                  holdst.fnFilter( $(this).child().val(), 5 );
               });

This does not make sense, we need to filter on $(this).val(), it's a
select element.

Test plan:
Place some holds
Hit the pending holds page
Use the "libraries" column filter and confirm that it works correctly

Signed-off-by: Andrew Nugged <nugged@gmail.com>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>