Describe the bug
The documentation and zookeeper dashboard use prometheus metrics prefixed with 'zookeeper_server_' which are no longer there.

For example zookeeper_server_connections

To Reproduce
Steps to reproduce the behavior:

1. docker run --rm -d -p 2181:2181 --name zk apachepulsar/pulsar:2.8.0 bin/pulsar zookeeper
2. curl -s localhost:8000/metrics |grep ^zoo
3. No zookeeper named metrics.
4. curl -s localhost:8000/metrics
5. Lots of output, so prometheus is working.
6. docker rm -f zk

Expected behavior
The documentation and grafana dasboards should use the correct metrics.