Update cadvisor repository (#1826)
Update cadvisor repository (#1826)

cAdvisor registry has moved from GCP project `google_containers` to `cadvisor`, ref: https://github.com/google/cadvisor/pull/2590

Signed-off-by: David Porter <aa743a0aaec8f7d7a1f01442503957f4d7a2d634@porter.me>
prometheus/docs,prometheus/docs,prometheus/docs