When initializing the `radicle-node` process, see
`radicle-node/src/runtime.rs`, an attempt is made to read from a node
announcement file.
This file is never written, therefore all of these reads fail.
Even though this caching mechanism might make sense or might have made
sense at some point, it is dead code now, and therefore removed.
Also, the fact that the file name was defined in the `radicle` crate is
ugly.
1cd3ad0784