kubeletstatsreceiver: set collect_all_network_interfaces on pods

[cazorla19]

This will continue fixing CDS-2133 by collecting pod network stats via kubeletstatsreceiver along with the node network stats.

receivers:
  kubeletstats:
    collection_interval: 20s
    auth_type: "serviceAccount"
    endpoint: "${env:K8S_NODE_NAME}:10250"
    insecure_skip_verify: true
    collect_all_network_interfaces:
      pod: true # this is the actual change
      node: true

In original PR #173 I've enabled it only on the node-level for now, since enabling it on the pod-level will increase network metrics cardinality without any useful case for our users. Now, after the chart deployment on the user environment, the metric stats still look incomplete without this flag being set, i.e. it still blindly relies on eth0 interface name.

This change should fix this issue.