Remove useless 'delete overviews' message.
Remove useless 'delete overviews' message.

The message was useless because it was being emitted for every sync update
regardless of whether overviews existed or not. And it was flooding Rollbar.

CartoDB/cartodb,splashblot/dronedb,splashblot/dronedb,CartoDB/cartodb,splashblot/dronedb,CartoDB/cartodb,CartoDB/cartodb,splashblot/dronedb,CartoDB/cartodb,splashblot/dronedb