OO-2646: dispose the runtime controller before creating a new one

src/main/java/org/olat/repository/ui/RepositoryEntryRuntimeController.java

@@ -912,6 +912,7 @@ public class RepositoryEntryRuntimeController extends MainLayoutBasicController
 			listenTo(runtimeController);
 			toolbarPanel.rootController(re.getDisplayname(), runtimeController);
 		} else if(security.canLaunch()) {
+			removeAsListenerAndDispose(runtimeController);
 			runtimeController = runtimeControllerCreator.create(ureq, getWindowControl(), toolbarPanel, re, reSecurity, assessmentMode);
 			listenTo(runtimeController);
 			toolbarPanel.rootController(re.getDisplayname(), runtimeController);