Enable insecure_skip_verify for kubelet scraping

[pintohutch]

We currently hardcode the scrape config for kubelet scraping. The configuration defaults to verifying the target certificate over https by leaving insecure_skip_verify as false.

However, this can result in errors on K8s clusters where nodes are not provisioned certificates to include the IP address in the certificate SAN field:

Get "https://10.223.3.45:10250/metrics/cadvisor": tls: failed to verify certificate: x509: cannot validate certificate for 10.223.3.45 because it doesn't contain any IP SAN

We should either:

1. Expose this field as a configuration option for kubelet scraping in the OperatorConfig, e.g.

collection:
  kubeletScraping:
    interval: 30s
    tlsSkipVerify: true

2. Change the default behavior to set insecure_skip_verify: true in the hardcoded config.

[pintohutch]

Actually looks like this is a duplicate of #223.

[pintohutch]

I'll just close this then and refer to that.