### Description From GitLab %"11.3", we migrated legacy artifacts from `ci_builds` to `ci_job_artfacts`. Legacy artifact rows have values in `size` column, whereas legacy artifact *metadata* rows do not have the values, because it didn't exist in `ci_builds`. We should calculate the size and fill it into the legacy artifact metadata rows. ### Solution All artifact files on gitlab.com are stored in object storage, so we need to execute `HEAD` command to get the `Content-length` of the file. This is cheap that it doesn't actually pull the whole data. ### Related - https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/18615 - https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17354 - https://gitlab.com/gitlab-org/gitlab-ce/issues/43599#note_61122784