Alerting: Update alerting cue definitions (#104053)

Co-authored-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>

pkg/tests/apis/openapi_test.go

@@ -93,6 +93,9 @@ func TestIntegrationOpenAPIs(t *testing.T) {
 	}, {
 		Group:   "playlist.grafana.app",
 		Version: "v0alpha1",
+	}, {
+		Group:   "notifications.alerting.grafana.app",
+		Version: "v0alpha1",
 	}}
 	for _, gv := range groups {
 		VerifyOpenAPISnapshots(t, dir, gv, h)