ArtifactUploader is different in CE and EE for 9.4

ZD: https://gitlab.zendesk.com/agent/tickets/80838

Customer observed that large artifact files were timing out. 8a417f5a should have fixed this, but I noticed somehow the changes in app/uploaders/artifact_uploader.rb landed in CE 9.4 but not in EE:

• https://gitlab.com/gitlab-org/gitlab-ee/blob/v9.4.3-ee/app/uploaders/artifact_uploader.rb
• https://gitlab.com/gitlab-org/gitlab-ce/blob/v9.4.3/app/uploaders/artifact_uploader.rb

I think we need to do an audit on how this happened, and then expand on that if there are potentially more files not merged properly.

/cc: @dblessing, @nick.thomas