Bug fix: Use ThreadSafeRandom in mt-log-test
Bug fix: Use ThreadSafeRandom in mt-log-test

This is another test that was using the normal distribution and
that started to fail on TSAN because the Random object is shared
across threads.

This just swaps Random for ThreadSafeRandom to avoid the race.

Change-Id: Id7077c4edd4356f6833a3745e9bb989b1274cec9
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/5095
Reviewed-by: Michael Percy <e07a1fd797b473a9c849e618aa2ce06d8055760b@cloudera.com>
Tested-by: jenkins

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