Update kafka sink maintainer
Update kafka sink maintainer

Signed-off-by: kokan <612fe515ae71366eab9f32c1307bdbff932735a2@balabit.com>

krzyzacy/heapster,whuwxl/heapster,piosz/heapster,piosz/heapster,krzyzacy/heapster,Stackdriver/heapster,Stackdriver/heapster,whuwxl/heapster,bluebreezecf/heapster,bluebreezecf/heapster