bar_mode(BarMode::Group) not working with second y axis

Added second y axis to bar_chart_with_error_bars from examples/statistical_charts

fn bar_chart_with_error_bars(show: bool, file_name: &str) {
    let trace_c = Bar::new(vec!["Trial 1", "Trial 2", "Trial 3"], vec![3, 6, 4])
        .error_y(ErrorData::new(ErrorType::Data).array(vec![1., 0.5, 1.5]));
    let trace_e = Bar::new(vec!["Trial 1", "Trial 2", "Trial 3"], vec![400, 700, 300])
        .y_axis("y2")
        .error_y(ErrorData::new(ErrorType::Data).array(vec![50.0, 100., 200.]));

    let mut plot = Plot::new();
    plot.add_trace(trace_c);
    plot.add_trace(trace_e);

    let layout = Layout::new()
        .bar_mode(BarMode::Group)
        .y_axis(Axis::new().title("Trace C"))
        .y_axis2(
            Axis::new()
                .title(Title::from("Trace E"))
                .side(AxisSide::Right),
        );
    plot.set_layout(layout);

    let path = write_example_to_html(&plot, file_name);
    if show {
        plot.show_html(path);
    }
}

Resulting chart. Overlay instead of group.

python version is also broken, but in different way - stack instead of group: https://github.com/plotly/plotly.py/issues/5582

Start with examples/statistical_charts and the bar_chart_with_error_bars entry point, then inspect how the generated chart configuration represents BarMode::Group when a trace uses y2. Compare the output with the shown result; done means the two y-axis bar traces render side by side in grouped mode rather than overlaying.