Remove complex password to fix tests

This is part of the changes of gitlab-cn/gitlab!404, the reason that
we do not need the whole changes of gitlab-cn/gitlab!404 is that the
complex password feature is not in 14-8-stable-jh, and login_spec.rb
has been updated in upstream to revert the complex password feature
(upstream part), see the commit 8e1715c7
for details.