EVAL_RESULT is logged under different logger for v4 and v6

The evaluation that is done as part of a client class being mentioned in the require-client-classes array is logged under different loggers in v4 and v6:

INFO  [kea-dhcp4.options] EVAL_RESULT Expression all evaluated to 1

INFO  [kea-dhcp6.dhcp6] EVAL_RESULT Expression all evaluated to 1

There seems to be no reason for it, and it can be confusing, and can lead to loss of log messages for users who use both v4 and v6 and filter messages by logger and expect to find the same message types in both logs.

First reported here: https://lists.isc.org/pipermail/kea-users/2022-June/003483.html