[Bug]: g2 当图例定位在左侧，如果是marginTop，效果是正常的，但是marginBottom对图例失效，效果有问题 #6771

Describe the bug / 问题描述

<!-- Failed to upload "image.png" -->

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
  marginBottom:222,
  height: 350
});
const shapeList = ['bowtie', 'smooth', 'hv', 'rect', 'hollowPoint'];

const data = [
  { genre: 'Sports', sold: 50 },
  { genre: 'Strategy', sold: 115 },
  { genre: 'Action', sold: 120 },
  { genre: 'Shooter', sold: 350 },
  { genre: 'Other', sold: 150 },
  { genre: 'Sp34orts', sold: 50 },
  { genre: 'Stra2tegy', sold: 115 },
  { genre: 'Action', sold: 120 },
  { genre: 'Shoo5ter', sold: 350 },
  { genre: 'Othe4r', sold: 150 },
  { genre: 'Sports', sold: 50 },
  { genre: 'Strat22egy', sold: 115 },
  { genre: 'Acti2on', sold: 120 },
  { genre: 'Sho23oter', sold: 350 },
  { genre: 'Oth3er', sold: 150 },
  { genre: 'S35ports', sold: 50 },
  { genre: 'Strat44egy', sold: 115 },
  { genre: 'Action', sold: 120 },
  { genre: 'Shooter', sold: 350 },
  { genre: 'Othe5r', sold: 150 },
  { genre: 'S8ports', sold: 50 },
  { genre: 'Str7ategy', sold: 115 },
  { genre: 'Act7ion', sold: 120 },
  { genre: 'Shoo2ter', sold: 350 },
  { genre: 'Oth4er', sold: 150 },
];
chart.options({
  type: 'interval',
  data,
  encode: { x: 'genre', y: 'sold', color: 'genre' },
  legend: {
    color: {
      maxCols:1,
      position:'left',
      // itemMarker
      itemMarker: (d, index) => shapeList[index],
      // itemLabel
      itemLabelFill: 'red',
      // itemValue
      itemValueText: (d, index) => data[index]['sold'],
      // itemBackground
      itemBackgroundFill: (d) => d.color,
      itemBackgroundFillOpacity: 0.2,
    },
  },
});

chart.render();

Reproduction link / 复现链接

No response

Steps to Reproduce the Bug or Issue / 重现步骤

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• IE (Nonsupport / 不支持)
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