add_filter( 'the_content', 'filter_test');  // also tried the `wp` hook
function filter_test($content){
  global $post;
  $post_slug = $post->post_name;
  if (get_post_type() == "post" && $post_slug != "allposts") {
    $content = preg_replace("/<strong>s+</strong>/",'',$content); // THIS LINE
    $content = preg_replace("/&nbsp;|^s*$/",'',$content);
    return $content;
  }
  return $content;
}