Pipeline partial is calling artifacts? which is slow
On the Pipelines index page we're executing a lot of times the method ci_build.artifacts?
And as we saw on https://gitlab.com/gitlab-org/gitlab-ce/issues/19273#note_12886990 checking for the present of a carrierwave file is not performance. Maybe we can just check the attribute presence or use a database query to return the build instances with artifacts no expired.