Fix pre-main-jh pipeline

What does this MR do and why?

1. skip upstream test, already raise question to upstream https://gitlab.com/gitlab-org/gitlab/-/merge_requests/136676#note_1706808565
2. fix test helper method gitlab_enable_admin_mode_sign_in, use enable_admin_mode! instread
3. fix jh/spec/lib/gitlab/email/message/account_validation_spec.rb, upstream rename verify-2.png to verify.png