Mixing stepped line and bars

### Expected behavior

Stepped line should follow before directive even when there are bars in same chart.

### Current behavior

Stepped line steps at the middle when bars are added to chart.

### Reproducible sample

v4.0.0

### Optional extra steps/info to reproduce

var ctx = document.getElementById("myChart");
var myChart = new Chart(ctx, {
type: 'line',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
stepped:'before'
},
{
label: 'Bars',
data: [12, 19, 3, 5, 2, 3],
type: 'bar'
}]
},
options: {
scales: {
x: {
stacked:true
},
y: {
stacked:true
}
}
}
});

### Possible solution

_No response_

### Context

_No response_

### chart.js version

Chart.js v4.0.0-alpha.3

### Browser name and version

Chrome on Android, Chromium on Linux

### Link to your project

_No response_