Fix missing metrics

[samjsong]

During testing we found the following metrics were missing:

• cloudprovider_.*_api_request_duration_seconds.*
  • this was due to the job changing from kube-controller-manager to kubelet
• container_memory_swap
  • this was due to a bug in the regex
• container_spec_.*
  • this was due to trying to add multiple regex matchers in the same writeRelabelConfigs section, which I believe is piped and therefore the metrics were being dropped
• node_memory_Free_bytes
  • this metric was renamed to node_memory_MemFree_bytes and node_memory_SwapFree_bytes

cc @ggarg2906sumo

[Gourav2906]

@samjsong please update metrics list document also with the updated list.

[samjsong]

@ggarg2906sumo done, thanks for the reminder!