For autopilot session registration, we accept default recommendations
from autopilot in order to weaken privacy obfuscation for the requested
features. Default privacy flags are supplied by ListFeatures and by
flags passed to the AddAutopilotSession request.
Privacy flags are ORed to combine to the weakest aggregated privacy
obfuscation in order to allow for multiple feature registration. In
order to preserve high privacy settings for a feature it should be
registered in an isolated manner.
