[FIX] web_calendar: translation for title on calendar form

The previous code (`parent.field_widget.string`) was returning the untranslated
action name (and why use parent anyway?)

Use the action name instead.

Closes #15207
opw-705938

addons/web_calendar/static/src/js/web_calendar.js

@@ -954,13 +954,7 @@ openerp.web_calendar = function(instance) {
             this.data_template = data_template || {};
         },
         get_title: function () {
-            var parent = this.getParent();
-            if (_.isUndefined(parent)) {
-                return _t("Create");
-            }
-            var title = (_.isUndefined(parent.field_widget)) ?
-                    (parent.string || parent.name) :
-                    parent.field_widget.string || parent.field_widget.name || '';
+            var title = (this.options.action)? this.options.action.name : '';
             return _t("Create: ") + title;
         },
         start: function () {