Chore: Drop xerrors dependency (#26718)

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

pkg/services/dashboards/dashboard_service_test.go

@@ -1,6 +1,7 @@
 package dashboards
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/grafana/grafana/pkg/infra/log"
@@ -10,7 +11,6 @@ import (
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/guardian"
 	. "github.com/smartystreets/goconvey/convey"
-	"golang.org/x/xerrors"
 )
 
 func TestDashboardService(t *testing.T) {
@@ -145,12 +145,12 @@ func TestDashboardService(t *testing.T) {
 				})
 
 				bus.AddHandler("test", func(cmd *models.ValidateDashboardAlertsCommand) error {
-					return xerrors.New("Alert validation error")
+					return fmt.Errorf("alert validation error")
 				})
 
 				dto.Dashboard = models.NewDashboard("Dash")
 				_, err := service.SaveDashboard(dto, false)
-				So(err.Error(), ShouldEqual, "Alert validation error")
+				So(err.Error(), ShouldEqual, "alert validation error")
 			})
 		})