The payload is already consumed within the InitialPacket unit. Consuming
it again resulted in UDP datagrams with multiple packets to ignore
the remaining packets in the same UDP datagram. The baseline changes
showing I being followed by a new H indicates that the INITIAL packet
was followed by a HANDSHAKE packet, but previously Zeek discarded
these.
A UDP datagram may contain multiple QUIC packets, but the parser so far
handled only the very first packet, ignoring any subsequent packets.
Fixes#4198
Seem reasonable give we log the server SCID. Interestingly, the Chromium
examples actually have zero length (empty) source connection IDs. I wonder
if that's part of their "protocol ossification avoidance" effort.
