Update queries to remove duplicate entries (CE version)

See merge request gitlab-org/gitlab-ce!15254

(cherry picked from commit 96764f26)

bc58f625 Adjust metrics to ignore Job tag to support k8s 1.7+
ab9acf1a Fix to use variable
41d1843f Fix CPU metric
712d5d89 Change label to be more consistent, not a series.
33fa4ef6 Uodate docs