MDL-42085 Enrol: Always apply enrolment duration.

Before the fix, the startdates and duration fields were integrated to HTML code only
when the user clicked on the collapsible region to see them.
It was wrong because their values were not sent by the form
if ever the user didn't expand this Enrolment options region.

enrol/manual/yui/quickenrolment/quickenrolment.js

@@ -156,11 +156,8 @@ YUI.add('moodle-enrol_manual-quickenrolment', function(Y) {
             }
 
             this.get(UEP.BASE).one('.'+CSS.SEARCHOPTIONS+' .'+CSS.COLLAPSIBLEHEADING).one('img').setAttribute('src', M.util.image_url(collapsedimage, 'moodle'));
-            this.get(UEP.BASE).one('.'+CSS.SEARCHOPTIONS+' .'+CSS.COLLAPSIBLEHEADING).once('click', function() {
-                // We want to do this just once, the first time the controls are shown.
-                this.populateStartDates();
-                this.populateDuration();
-            }, this);
+            this.populateStartDates();
+            this.populateDuration();
             this.get(UEP.BASE).one('.'+CSS.SEARCHOPTIONS+' .'+CSS.COLLAPSIBLEHEADING).on('click', function(){
                 this.get(UEP.BASE).one('.'+CSS.SEARCHOPTIONS+' .'+CSS.COLLAPSIBLEHEADING).toggleClass(CSS.ACTIVE);
                 this.get(UEP.BASE).one('.'+CSS.SEARCHOPTIONS+' .'+CSS.COLLAPSIBLEAREA).toggleClass(CSS.HIDDEN);