ContainerBalancer incorrectly exits an iteration early without checking move results.

In ContainerBalancer#doIteration:

      IterationResult result = checkConditionsForBalancing();
      if (result != null) {
        LOG.info("Exiting current iteration: {}", result);
        return result;
      }

Leads to the iteration ending early without checking move results and updating metrics. This bug can be reproduced by setting the maxSizeToMovePerIteration to a small value such as 5GB that allows one container move before ending the iteration.