cabana: reduce the number of ticks on the Y-axis (#27964)

tools/cabana/chart/chart.cc

@@ -331,7 +331,7 @@ void ChartView::updateAxisY() {
   }
 
   double delta = std::abs(max - min) < 1e-3 ? 1 : (max - min) * 0.05;
-  auto [min_y, max_y, tick_count] = getNiceAxisNumbers(min - delta, max + delta, axis_y->tickCount());
+  auto [min_y, max_y, tick_count] = getNiceAxisNumbers(min - delta, max + delta, 3);
   if (min_y != axis_y->min() || max_y != axis_y->max() || y_label_width == 0) {
     axis_y->setRange(min_y, max_y);
     axis_y->setTickCount(tick_count);