* HADOOP-16579 - Upgrade to Apache Curator 4.2.0 and ZooKeeper 3.5.5
- Add a static initializer for the unit tests using ZooKeeper to enable
the four-letter-words diagnostic telnet commands. (this is an interface
that become disabled by default, so to keep the ZooKeeper 3.4.x behavior
we enabled it for the tests)
- Also fix ZKFailoverController to look for relevant fail-over ActiveAttempt
records. The new ZooKeeper seems to respond quicker during the fail-over
tests than the ZooKeeper, so we made sure to catch all the relevant records
by adding a new parameter to ZKFailoverontroller.waitForActiveAttempt().
Co-authored-by: Norbert Kalmár <nkalmar@cloudera.com>
