[dnsproxy] use dns block by default
[dnsproxy] use dns block by default

(cherry picked from commit 0350def40c5506c924cd96f32810c68e0fd9dc8e)

firewalla/firewalla,MelvinTo/firewalla,MelvinTo/firewalla,firewalla/firewalla,firewalla/firewalla,firewalla/firewalla,MelvinTo/firewalla,MelvinTo/firewalla,MelvinTo/firewalla,firewalla/firewalla