Pulsar components not starting when user provided zookeepers are used

[Shohou]

Describe the bug
Pulsar components not starting when user provided zookeepers are used

To Reproduce
Use the following values.yaml when installing pulsar

namespace: pulsar

components:
  zookeeper: false

volumes:
  persistence: true
  local_storage: false

monitoring:
  prometheus: false
  grafana: false
  node_exporter: false
  alert_manager: false

pulsar_metadata:
  userProvidedZookeepers: "zookeeper.zookeeper:2181"

bookkeeper:
  replicaCount: 2
  volumes:
    journal:
      size: 2Gi
    ledgers:
      size: 5Gi

broker:
  replicaCount: 1

proxy:
  replicaCount: 1

Execute kubectl logs pulsar-bookie-0 -n pulsar -c pulsar-bookkeeper-verify-clusterid and see repeating exceptions

08:28:20.955 [main-SendThread(pulsar-zookeeper:2181)] WARN  org.apache.zookeeper.ClientCnxn - Session 0x0 for server pulsar-zookeeper:2181, unexpected error, closing socket connection and attempting reconnect
java.lang.IllegalArgumentException: Unable to canonicalize address pulsar-zookeeper:2181 because it's not resolvable
        at org.apache.zookeeper.SaslServerPrincipal.getServerPrincipal(SaslServerPrincipal.java:71) ~[org.apache.pulsar-pulsar-zookeeper-2.6.0.jar:2.6.0]
        at org.apache.zookeeper.SaslServerPrincipal.getServerPrincipal(SaslServerPrincipal.java:39) ~[org.apache.pulsar-pulsar-zookeeper-2.6.0.jar:2.6.0]
        at org.apache.zookeeper.ClientCnxn$SendThread.startConnect(ClientCnxn.java:1087) ~[org.apache.pulsar-pulsar-zookeeper-2.6.0.jar:2.6.0]
        at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1139) [org.apache.pulsar-pulsar-zookeeper-2.6.0.jar:2.6.0]
08:28:22.056 [main-SendThread(pulsar-zookeeper:2181)] ERROR org.apache.zookeeper.client.StaticHostProvider - Unable to resolve address: pulsar-zookeeper:2181
java.net.UnknownHostException: pulsar-zookeeper
        at java.net.InetAddress.getAllByName0(InetAddress.java:1281) ~[?:1.8.0_252]
        at java.net.InetAddress.getAllByName(InetAddress.java:1193) ~[?:1.8.0_252]
        at java.net.InetAddress.getAllByName(InetAddress.java:1127) ~[?:1.8.0_252]
        at org.apache.zookeeper.client.StaticHostProvider$1.getAllByName(StaticHostProvider.java:92) ~[org.apache.pulsar-pulsar-zookeeper-2.6.0.jar:2.6.0]
        at org.apache.zookeeper.client.StaticHostProvider.resolve(StaticHostProvider.java:147) [org.apache.pulsar-pulsar-zookeeper-2.6.0.jar:2.6.0]
        at org.apache.zookeeper.client.StaticHostProvider.next(StaticHostProvider.java:375) [org.apache.pulsar-pulsar-zookeeper-2.6.0.jar:2.6.0]
        at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1137) [org.apache.pulsar-pulsar-zookeeper-2.6.0.jar:2.6.0]

Expected behavior
Pulsar starts and connects to provided zookeeper.

Additional context

$ helm show chart apache/pulsar
apiVersion: v1
appVersion: "1.0"
description: Apache Pulsar Helm chart for Kubernetes
home: https://pulsar.apache.org
icon: http://pulsar.apache.org/img/pulsar.svg
maintainers:
- email: dev@pulsar.apache.org
  name: The Apache Pulsar Team
name: pulsar
sources:
- https://github.com/apache/pulsar
version: 2.6.0

[Shohou]

this was fixed at some point and works in version 2.7.0