MAJOR: config: prevent QUIC with clients privileged port by default

MAJOR: config: prevent QUIC with clients privileged port by default

Previous commit introduce new protection mechanism to forbid
communications with clients which use a privileged source port. By
default, this mechanism is disabled for every protocols.

This patch changes the default value and activate the protection
mechanism for QUIC protocol. This is justified as it is a probable sign
of DNS/NTP amplification attack.

This is labelled as major as it can be a breaking change with some
network environments.