Support i18n on 'GitLab' in user_spec.rb

What does this MR do and why?

Make the string GitLab in spec support i18n.

This i18n problem causes an error in Jihu's pipeline:

• https://jihulab.com/gitlab-cn/gitlab/-/jobs/11853599#L1330
• https://jihulab.com/gitlab-cn/gitlab/-/jobs/11853598#L981

1) User Cluster when user does have a cluster and visits cluster page when signed in user is an admin in admin_mode can visit the clusters index page
     Failure/Error: expect(page).to have_title("Kubernetes Clusters · #{group.name} · GitLab")
       expected "Kubernetes Clusters · group1 · JiHu GitLab" to include "Kubernetes Clusters · group1 · GitLab"

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cc @xfyuan @qianzhangxa