Remove SimpleHttpFetcher.finalize() method

[aecio]

Overriding the Object::finalize() method is deprecated since Java 9, and should be removed. One option would be to replace it with a close() method and make SimpleHttpFetcher implement the Closeable interface.

Current finalize() implementation:

    @Override
    protected void finalize() {
        monitor.interrupt();
        _connectionManager.shutdown();
        IOUtils.closeQuietly(_httpClient);
        _httpClient = null;
    }