Build AMIs for all tags except RC and auto-deploy ones

Initially we wanted to only have the latest AMI available at any point of time. So we wrote the code to delete the previos images, but marked it as dry run to ensure it did its job without actually touching anything. But we never removed that dry run flag.

Also, since we have customers who may intentionally remain on older versions, we do have to maintain older images. So there is no need for this code anymore.