Replace weightby

The weightby mechanism is rarely used to do what it is intended for, which is manual adjustments to the load balancing alogorithms, and most of the time it is abused to forcibly discard a server from routing.

The use of conditional server use, or in other words priority based usage, is a valid use-case as in some scenarios a local server is always better compared a remote one but the remote server should be usable in case the local one fails.