Skip email_opt_in_registration_spec.rb

What does this MR do and why?

Fix pipeline: https://jihulab.com/gitlab-cn/gitlab/-/pipelines/3416146

Upstream 改了很多注册流程相关的代码：https://gitlab.com/gitlab-org/gitlab/-/merge_requests/164411 ，极狐已经覆盖了这部分内容，所以先跳过测试。

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