Avoid nested forms

What does this MR do and why?

Fix pipeline: https://jihulab.com/gitlab-cn/gitlab/-/pipelines/1300758

Why

昨天合入的 MR !1757 (merged) 引入一个 bug：出现了嵌套的 form。

嵌套 form 是不被允许的：https://stackoverflow.com/a/379622/19717196 。

同时这样的嵌套样式导致前端 form 表单的渲染出错，第一个 form 表单没有被正确加载出来，导致点击按钮时无法发出正确的请求：

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