This vertical line appears by default on highstock but on highcharts it's null by default. You can enable it setting tooltip crosshairs like here.
To highlight all your series on the same y value you have to set shared as true like here.

tooltip: {
    crosshairs: {
        color: 'green',
        dashStyle: 'solid'
    shared: true

You can style your crosshairs looking the following reference.

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