Convert scan servers to use rendezvous hashing #5928
Description
Is your feature request related to a problem? Please describe.
The current scan server code uses normal hashing across the set of scan servers. This means any change to the number of running scan servers can cause extreme differences in where client requests are issued.
Describe the solution you'd like
The scan server selection code should use rendezvous hashing in order to minimize tablet request churn across the scan servers.