PCT-637: Query Analytics does not handle MySQL Restart

Done

However, I'm afraid that FileIntervalIter goroutine might access mysqlConn.Connect/Close/Set at the same time as the goroutine with check if mysql was restarted. @daniel-nichter What you think? Should I protect mysql.Connection with mutex?
Yes, you'e correct.  `mock.ConnectionFactory` can be created with either a null or mock MySQL client, so it returns whatever it's created with.  Only case in which this might matter: sometimes in mock objects we add methods not in the interface, (e.g. `Reset()` and other helper methods for the test case), in which case, since this single factor returns an interface and not specific objects, you can't do `conn.Reset()` because Go will complain like "mysql.Connector interface has no Reset() method", or something like iirc.