OPENOLAT-586: Set BeginEnd option invisible in exam mode if set to automatic

src/main/java/org/olat/course/assessment/ui/mode/AssessmentModeEditController.java

@@ -222,6 +222,7 @@ public class AssessmentModeEditController extends FormBasicController {
 		if(assessmentMode.isManualBeginEnd()) {
 			startModeEl.select(startModeKeys[1], true);
 		} else {
+			startModeEl.setVisible(false);
 			startModeEl.select(startModeKeys[0], true);
 		}
 		startModeEl.setEnabled(status != Status.end);