fix(scaletest/dashboard): fix early exit due to validate (#10212)

scaletest/dashboard/run.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"io"
+	"math/rand"
 	"time"
 
 	"golang.org/x/xerrors"
@@ -35,6 +36,9 @@ func NewRunner(client *codersdk.Client, metrics Metrics, cfg Config) *Runner {
 	if cfg.Screenshot == nil {
 		cfg.Screenshot = Screenshot
 	}
+	if cfg.RandIntn == nil {
+		cfg.RandIntn = rand.Intn
+	}
 	return &Runner{
 		client:  client,
 		cfg:     cfg,