launcher: stop the shadowed-hostname test asserting the local machine's ports

It counted Pass/Warn/Fail across the whole preflight run, and `backend_reachable`
opens real sockets — so the aggregate silently asserted that the machine running
the suite has the OpenFUT blaze-redirector and account ports open. True on the
server host, false everywhere else, including the game machine where anyone
building the launcher would run it. Predates this branch; found by running the
suite on .105 instead of only here. Now asserts the hostname check itself, which
is what the test is named for.

src/preflight.rs

@@ -402,15 +402,24 @@ mod tests {
 
     /// A shadowed hostname must not be counted as a reason to expect failure.
     /// This is the exact case the first version got wrong.
+    ///
+    /// Asserts the hostname check itself rather than counting states across the
+    /// whole run: `backend_reachable` opens real sockets, so an aggregate count
+    /// silently asserts that THIS machine has the OpenFUT ports open. That made
+    /// the test pass only on the server host and fail on the game machine, which
+    /// is precisely where someone building the launcher runs the suite.
     #[test]
     fn a_shadowed_hostname_is_a_warning_not_a_failure() {
         let mut c = cfg();
         c.openfut_server_host = "127.0.0.2".into();
         c.ea_hostnames = vec!["localhost".into()];
-        c.fifa17_tools_dir = "/nonexistent/openfut-tools".into();
-        let checks = run(&c);
-        assert_eq!(failures(&checks), 0, "must not be reported as fatal");
-        assert_eq!(warnings(&checks), 1);
+        let check = hostname_mapping(&c);
+        assert_eq!(check.state, State::Warn, "{}", check.detail);
+        assert!(
+            check.detail.contains("localhost"),
+            "the warning must name the shadowed host: {}",
+            check.detail
+        );
     }
 
     #[test]