test: move test-net-connect-handle-econnrefused

The port used in the test could be taken by another process before
the callback of `server.close()` is called. Move it to sequential.

PR-URL: #27014
Fixes: #26907
Refs: #18257 (comment)
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

Author: lpinca