Bug 35280: Fix patron attributes "clear" link in OPAC patron entry form

This patch makes a minor correction to the JavaScript controlling the
behavior of the "clear" link which appears on the patron entry form next
to patron attribute <select>s or <textarea>s which are editable in the
OPAC.

To test, apply the patch and create patron attributes
which have both "Display in OPAC" and "Editable in OPAC" checked.

- Create one which is tied to an authorized value, and one which isn't.
- Log in to the OPAC and click the "Personal details" tab.
- In the entry form, find the patron attribute fields under the
  Additional information" heading..
- Select a value in the dropdown, and enter text in the textarea.
- Confirm that clicking the corresponding "Clear" link for each works as
  expected.

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>
(cherry picked from commit 3a027a0da9)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>

koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-memberentry.tt

@@ -1203,12 +1203,11 @@
                 [% END %]
             [% END %]
 
-            $(".patron-attributes").on( 'click', '.clear-attribute', function() {
+            $(".patron-attributes").on( 'click', '.clear-attribute', function(e) {
+                e.preventDefault();
                 $(this).parent()
-                    .find('textarea').attr('value', '').end()
-                    .find('select').attr('value', '').end();
-
-                return false;
+                    .find('textarea').val("").end()
+                    .find('select').val("").end();
             } );
 
             $(".patron-attributes").on( 'click', '.clone-attribute', function() {