Sugar defeats the point of trying to clean up candida. And I can tell you from personal experience, if I eat sugar in any form, I feel like crap. With regards to milk, when I do drink it, I only buy organic that is hormone and antiobiotic free.
The sugar is used up in the fermentation process. The bacteria ferment the sugars creating beneficial acids. This is why the kefir should be fermented long enough to get rid of as much sugar as possible.