Increase max_connections_pending_in and max_connections_pending_out

[sandreae]

I noticed while doing some network testing that these two limits can easily get hit when many peers are registered on a relay. This seems to be because a "pending" connection includes attempts to peers who are not currently online. I suggest increasing this value from 8 to 16 which is then the same as max_connections_in and max_connections_out.