Apply cargo fmt to node module and handshake tests

Exposed by the rustfmt toolchain-pin fix now that rustfmt runs under
the pinned 1.94.1 toolchain in CI. Mechanical formatting changes:

- src/node/mod.rs: collapse EthernetTransport::new let-binding onto
  one line (fits within width limit)
- src/node/tests/handshake.rs: reorder imports (super::* after
  specific import) and expand two assert_eq! calls to multi-line form

src/node/mod.rs

@@ -734,8 +734,7 @@ impl Node {
 
             for (name, eth_config) in eth_instances {
                 let transport_id = self.allocate_transport_id();
-                let eth =
-                    EthernetTransport::new(transport_id, name, eth_config, packet_tx.clone());
+                let eth = EthernetTransport::new(transport_id, name, eth_config, packet_tx.clone());
                 transports.push(TransportHandle::Ethernet(eth));
             }
         }