Tests for the way db-analyser interprets a node configuration file.

The parsing itself is cardano-config's job, but db-analyser derives a few things from the result (the initial nonce, the hard-fork triggers, the LedgerDB backend), and those derivations are what these tests pin down. They run against the node configuration in disk/config, so they also catch the silent failure mode of cardano-config ignoring a key db-analyser depends on.