This column was blank before. It contain one or two pieces of
information:
* Job duration
* Job completion timestamp
For brevity, use `Timing` as the header.
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/62347
Rename other URL generators
admin_builds_path -> admin_jobs_path
Fix tests and more renaming
Fix more tests
Also change build_id to job_id in the controller