Client-side configuration of DummyPacketInterval or isc_dpb_dummy_packet_interval has no effect

[mrotteveel]

As far as I can tell from the code, isc_dpb_dummy_packet_interval, and by extension, the DummyPacketInterval setting has no effect when configured client-side, as isc_dpb_dummy_packet_interval does not seem to get used server-side, other than setting the field dpb_dummy_packet_interval of DatabaseOptions, which is never read.