Generated summary for Scatterplot describe only first group of points

[ilyabrower]

Describe the bug

For Scatterplot with data, which has more then one YAxe, for example

const data = Array(10)
  .fill({})
  .map((d, i) => ({
    x: i,
    y1: Math.random() * 10,
    y2: Math.random() * 10,
    value: i,
  }));

summary will be generated only for y1.

Expected behavior
The summary will have both y1 and y2 data.