Update layout.html

[Dacong-wu]

增加移除 sidebar 组件的功能 问题背景：当我在开发 photos 页面的时候，发现根本无法移除 sidebar 导致这片区域形成了浪费

[f2c-ci-robot[bot]]

@Dacong-wu: Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

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[Dacong-wu]

/assign @johnniang

[f2c-ci-robot[bot]]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[Dacong-wu]

OK