第三方账号登录后，页面语言未显示为中文

Summary

第三方账号登录后，页面语言未显示为中文

（默认语言设置为中文）的遗留问题，计划在15.2进行fix，创建该 Issue 进行 Track

Steps to reproduce

1. 进入登录页面
2. 通过第三方账号进行登录
3. 登录成功后，查看页面语言设置

Example Project

What is the current bug behavior?

页面默认语言显示为英文

What is the expected correct behavior?

页面默认语言显示为中文

Relevant logs and/or screenshots

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes