Remove NodeManager dependency from ServerInfo

This commit removes the NodeManager dependecny from ServerInfo so it works equally with virtual storage scoped primaries or repository specific primaries configured.

The RPC is fairly eccentric. It tries to give an illusion of a single storage responding, which does not really suit well with the multiple storages sitting behind a Praefect. It previously relayed the information from the virtual storage's primary. With repository specific primaries, none of the storages have a special status. As such, we'll just return the response from a random storage from now on. Given the primary might change due to a failover, the client's can't rely on the returned response anyway.

Related to #3492 (closed)