The confirmation instructions email template should be updated for JH

Problem to solve

A new user receives a confirmation instructions email from JiHu GitLab after signing up. Some content should be update accordingly

1. "Thanks for signing up GitLab" - should be "极狐GitLab"
2. "Testing custom mail - xxx" - It seems some test message, should be removed
3. The footer links should be changed to JiHu URLs.