ZOOKEEPER-3801: update CI link to https://ci-hadoop.apache.org/view/ZooKeeper/
Author: Enrico Olivelli <eolivelli@apache.org>
Reviewers: Christopher Tubbs <ctubbsii@apache.org>, Mate Szalay-Beko <symat@apache.org>
Closes #1440 from eolivelli/fix/ZOOKEEPER-3801-2