refactor(settings): remove Hide threads without images setting

5chan boards enforce requirePostLinkIsMedia/requirePostLink at subplebbit level; client-side filter redundant.

public/translations/zh/default.json

@@ -143,7 +143,6 @@
   "filters": "过滤器",
   "image_size": "图像尺寸",
   "show_op_comment": "显示楼主评论",
-  "hide_threads_without_images": "隐藏没有图片的主题",
   "on": "开启",
   "off": "关闭",
   "small": "小",
@@ -197,7 +196,6 @@
   "crypto_address_yours": "加密地址属于此帐户。",
   "delete_wallet": "删除钱包",
   "last_bumped": "最后提升",
-  "threads_without_images_tip": "仅显示链接到可嵌入媒体的帖子",
   "fit_expanded_images_to_screen": "适应扩展图像到屏幕",
   "fit_expanded_images_to_screen_tip": "将扩展图像限制为浏览器的宽度和高度",
   "hide_avatars_tip": "不显示用户显示名称旁边的头像",