neon: Only show reload button during login when server is already set

packages/neon/lib/src/pages/login.dart

@@ -141,11 +141,13 @@ class _LoginPageState extends State<LoginPage> {
                         icon: const Icon(Icons.arrow_back),
                       ),
                       actions: [
+                        if (serverConnectionStateSnapshot.data != null) ...[
                           IconButton(
                             onPressed: _loginBloc.refresh,
                             icon: const Icon(Icons.refresh),
                           ),
                         ],
+                      ],
                     )
                   : null,
               body: serverConnectionStateSnapshot.data == ServerConnectionState.success