[FIX] survey: support custom server date format in (frontend) surveys

The library moment.js does not support custom date formats anymore.
The following warning is given:
Deprecation warning: value provided is not in a recognized ISO format.
As a result, the moment contains 'Invalid Date',
which would remove possibility to complete a survey containing a date
in any format different than the default.

opw 1930152

closes odoo/odoo#30894

addons/survey/static/src/js/survey.js

@@ -134,7 +134,7 @@ if(!the_form.length) {
             var date_fields = $form.find('div.date > input.form-control');
             for (var i=0; i < date_fields.length; i++) {
                 var el = date_fields[i];
-                var moment_date = el.value !== '' ? moment(el.value) : '';
+                var moment_date = el.value !== '' ? field_utils.parse.date(el.value) : '';
                 if (moment_date) {
                     moment_date.toJSON = function () {
                         return this.clone().locale('en').format('YYYY-MM-DD');