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?
I don't understand. currentUptime is fetched directly from mysql. previousUptime is also fetched directly from mysql but this is from previous check. If agent couldn't connect to mysql for 120s then the comparision is going to look like this `180s < 60s` which evaluates to false - server was not restarted and this is correct.