test: remove call to `net.Socket.resume()`

In test parallel/child-process-fork-net2 `net.Socket.resume()` is not necessary
since `net.Socket.pause()` is never called.

PR-URL: https://github.com/nodejs/node/pull/8679
Refs: https://github.com/nodejs/node/issues/4640
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>

test/parallel/test-child-process-fork-net2.js

@@ -109,10 +109,6 @@ if (process.argv[2] === 'child') {
         console.error('[m] CLIENT: close event');
         disconnected += 1;
       });
-      // XXX This resume() should be unnecessary.
-      // a stream high water mark should be enough to keep
-      // consuming the input.
-      client.resume();
     }
   });