Since sbws is only building 2 hop paths, there is no need to add random
relays to the path, or convert back and forth between fingerprint and
``Relay`` objects.

This will eliminate the circuit errors:
- Tor seems to no longer think XXX is a relay
- Can not build a circuit, no path.
- Can not build a circuit with the current relays.
If a relay is not longer running when attempting to build the circuit,
it will probably fail with one of the other circuit errors: TIMEOUT,
DESTROYED or CHANNEL_CLOSED.

Closes: #40027