Add metrics for monitoring canary tracks for CPU and Memory
This is related to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/15201, but implements the updates to the metrics file. This is EE only, because this feature is just for EEP but we don't have a way yet to restrict canary support for just EE. We will open a new issue for that and track.
Parent issue: https://gitlab.com/gitlab-org/gitlab-ee/issues/2594