Add zookeeper-observ-lib and uses it inside kafka-observ-lib/kafka-mixin
Drop old zookeeper dashboard from kafka-mixin
Add support for metricsSource: prometheus_old in jvm-observ-lib. This is metric style used in prometheus instrumentation prior to 1.0.0 version (in zookeeper metrics for example)
Zookeeper dashboard in Kafka now looks like this:
With all JVM related rows imported from jvm-observ-lib but collapsed, to let users focus on zookeeper metrics by default: https://github.com/grafana/jsonnet-libs/pull/1220