fix(components): [cascader] fix SVG generated mask the menu when scroll

[Fiona2016]

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descriptions:
when scroll too long, the svg will hide the menu.

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[github-actions]

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[github-actions]

[Fiona2016]

1. the same issue like this: [bug report] the SVG generated by cascade will mask the hover event of Li element ElemeFE/element#21505
2. when threshold set 2s, the problem will be quite evident.

[btea]

Can you provide a repro link using playground? The link previously provided doesn't seem to work.