Alerting: enable e2e tests to run in production mode (#45073)

* Alerting: run e2e tests in production mode

* adapt expected messages

* switch expected and actual to have the right order

pkg/tests/api/alerting/api_available_channel_test.go

@@ -22,6 +22,7 @@ func TestAvailableChannels(t *testing.T) {
 		DisableLegacyAlerting: true,
 		EnableUnifiedAlerting: true,
 		DisableAnonymous:      true,
+		AppModeProduction:     true,
 	})
 
 	grafanaListedAddr, store := testinfra.StartGrafana(t, dir, path)