It's been linked with various performance issues, either by causing
them or making them worse. One example is #1634, and also recently
I have investigated continuous performance degradation that was also
linked to defrag on idle activity.
Until we can figure out how to reduce its impact, we should disable it.
Signed-off-by: Glauber Costa <glauber@glauber.scylladb>
Message-Id: <20170627201109.10775-1-glauber@scylladb.com>
(cherry picked from commit f3742d1e38)