Kea's v6 server seems to be missing some debug logging for DHCP6_PACKET_SEND

name: Kea's v6 server seems to be missing some logging for DHCP6_PACKET_SEND
about: a customer has pointed out that the v4 and v6 servers log differently and the v6 server seems to be missing some logging.

Describe the bug

A support customer has reported to us (via support ticket #14897) that their debug logging for the v6 server is missing messages for DHCP6_PACKET_SEND. Examples of the difference in logging between the v4 and v6 servers can be found on the linked support ticket (omitted here because the log excerpts contain names and addresses belonging to the customer.)

We discussed in the Kea/Support meeting (19 June 2019) and concluded that the omission is unintended and is in error. Customer would like for it to be fixed.