Alerting: update authorization logic to use proper legacy roles when fine-grained access is disabled (#46931)

* require legacy Editor for post, put, delete endpoints
* require user to be signed in on group level because handler that checks that user has role Editor does not check it is signed in

pkg/services/ngalert/api/generated_base_api_prometheus.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/grafana/grafana/pkg/api/response"
 	"github.com/grafana/grafana/pkg/api/routing"
+	"github.com/grafana/grafana/pkg/middleware"
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/ngalert/metrics"
 )
@@ -81,5 +82,5 @@ func (api *API) RegisterPrometheusApiEndpoints(srv PrometheusApiForkingService,
 				m,
 			),
 		)
-	})
+	}, middleware.ReqSignedIn)
 }