feat(go): add load simulator hold mode

go/vehicle-gateway/internal/loadsim/runner.go

@@ -37,6 +37,9 @@ func (r Runner) Run(ctx context.Context, cfg Config) (Stats, error) {
 	if err != nil {
 		return Stats{}, err
 	}
+	if !cfg.SendFrames {
+		payload = nil
+	}
 	dial := r.Dial
 	if dial == nil {
 		dialer := &net.Dialer{Timeout: 5 * time.Second, KeepAlive: 30 * time.Second}
@@ -68,7 +71,11 @@ func (r Runner) Run(ctx context.Context, cfg Config) (Stats, error) {
 			go func() {
 				defer wg.Done()
 				defer conn.Close()
-				writeLoop(runCtx, conn, payload, cfg.SendInterval, &stats)
+				if cfg.SendFrames {
+					writeLoop(runCtx, conn, payload, cfg.SendInterval, &stats)
+					return
+				}
+				<-runCtx.Done()
 			}()
 		}
 	}