Chore: Drop xerrors dependency (#26718)

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

pkg/services/alerting/engine.go

@@ -2,6 +2,7 @@ package alerting
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"
 
@@ -16,7 +17,6 @@ import (
 	"github.com/grafana/grafana/pkg/services/rendering"
 	"github.com/grafana/grafana/pkg/setting"
 	"golang.org/x/sync/errgroup"
-	"golang.org/x/xerrors"
 )
 
 // AlertEngine is the background process that
@@ -215,9 +215,9 @@ func (e *AlertEngine) processJob(attemptID int, attemptChan chan int, cancelChan
 		evalContext.Rule.State = evalContext.GetNewState()
 		if err := e.resultHandler.handle(evalContext); err != nil {
 			switch {
-			case xerrors.Is(err, context.Canceled):
+			case errors.Is(err, context.Canceled):
 				e.log.Debug("Result handler returned context.Canceled")
-			case xerrors.Is(err, context.DeadlineExceeded):
+			case errors.Is(err, context.DeadlineExceeded):
 				e.log.Debug("Result handler returned context.DeadlineExceeded")
 			default:
 				e.log.Error("Failed to handle result", "err", err)