[v9.2.x] Alerting: Use correct response body for silence post API (#57126)

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

pkg/services/ngalert/api/api_alertmanager.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/go-openapi/strfmt"
+
 	"github.com/grafana/grafana/pkg/api/response"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/models"
@@ -85,7 +86,9 @@ func (srv AlertmanagerSrv) RouteCreateSilence(c *models.ReqContext, postableSile
 
 		return ErrResp(http.StatusInternalServerError, err, "failed to create silence")
 	}
-	return response.JSON(http.StatusAccepted, util.DynMap{"message": "silence created", "id": silenceID})
+	return response.JSON(http.StatusAccepted, apimodels.PostSilencesOKBody{
+		SilenceID: silenceID,
+	})
 }
 
 func (srv AlertmanagerSrv) RouteDeleteAlertingConfig(c *models.ReqContext) response.Response {