Remove noisy stack config policy log line

[pebrc]

cloud-on-k8s/pkg/controller/stackconfigpolicy/secure_setings.go

Line 32 in 1fa362a

log.Info("Unknown resource kind, stackconfigpolicy only monitors Elasticsearch and Kibana resources", "resource kind", resourceKind)

This turns out to be quite a noise log line that we probably should remove or adjust since Logstash can have secure settings as well and we will end up with many instances of this message in the logs that might alert users even though there is no problem.