Add allowlist for subcmds

What does this MR do and why?

Resolve https://jihulab.com/gitlab-cn/gitlab/-/issues/3267

禁掉在极狐 GitLab 不可用的几个 subcmds。

除此之外，其他的所有 subcmds 均已经过验证，可被用户正常使用。

禁用命令	禁用的原因
download	download 的作用是下载 changes，GitLab 中不存在 changes 的概念
cherry-pick	cherry-pick 操作的对象也是 changes，GitLab 中不存在 changes 的概念
gitc-delete	gitc 是 Google 内部开发工具，我们不需要它
gitc-init	gitc 是 Google 内部开发工具，我们不需要它

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How to set up and validate locally

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MR acceptance checklist

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