Navigation: Correctly create `Alerts and incidents` section when using legacy alerting (#64924)

check for legacy alerting node as well

pkg/services/navtree/models.go

@@ -43,6 +43,7 @@ const (
 	NavIDAdmin              = "admin"
 	NavIDAlertsAndIncidents = "alerts-and-incidents"
 	NavIDAlerting           = "alerting"
+	NavIDAlertingLegacy     = "alerting-legacy"
 	NavIDMonitoring         = "monitoring"
 	NavIDReporting          = "reports"
 	NavIDApps               = "apps"

pkg/services/navtree/navtreeimpl/applinks.go

@@ -179,6 +179,10 @@ func (s *ServiceImpl) processAppPlugin(plugin plugins.PluginDTO, c *contextmodel
 func (s *ServiceImpl) addPluginToSection(c *contextmodel.ReqContext, treeRoot *navtree.NavTreeRoot, plugin plugins.PluginDTO, appLink *navtree.NavLink) {
 	// Handle moving apps into specific navtree sections
 	alertingNode := treeRoot.FindById(navtree.NavIDAlerting)
+	if alertingNode == nil {
+		// Search for legacy alerting node just in case
+		alertingNode = treeRoot.FindById(navtree.NavIDAlertingLegacy)
+	}
 	sectionID := navtree.NavIDApps
 
 	if navConfig, hasOverride := s.navigationAppConfig[plugin.ID]; hasOverride {

public/app/features/alerting/routes.tsx

@@ -18,7 +18,7 @@ const legacyRoutes: RouteDescriptor[] = [
   {
     path: '/alerting',
     component: () =>
-      config.featureToggles.topnav ? <NavLandingPage navId="alerting" /> : <Redirect to="/alerting/list" />,
+      config.featureToggles.topnav ? <NavLandingPage navId="alerting-legacy" /> : <Redirect to="/alerting/list" />,
   },
   {
     path: '/alerting/list',