Reduce the days that artifacts are stored for our builds from 14 to 7
These artifacts are for periods longer than a day when performing a release. The release task can happend days after the staging task.
14 days has been putting a little too much pressure on our current storage for artifacs. We should be able to reduce it to 7, still have a comfortable window for releases, but require less storage.
Related to: https://gitlab.com/gitlab-com/infrastructure/issues/2777