refactor(settings): remove Hide threads without images setting

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

public/translations/en/default.json

@@ -146,7 +146,6 @@
   "filters": "filters",
   "image_size": "image size",
   "show_op_comment": "Show OP Comment",
-  "hide_threads_without_images": "Hide Threads Without Images",
   "on": "on",
   "off": "off",
   "small": "small",
@@ -204,7 +203,6 @@
   "delete_wallet": "Delete Wallet",
   "delete_avatar": "Delete Avatar",
   "last_bumped": "Last Bumped",
-  "threads_without_images_tip": "Only display threads that link to embeddable media",
   "fit_expanded_images_to_screen": "Fit expanded images to screen",
   "fit_expanded_images_to_screen_tip": "Limit expanded images to both browser width and height",
   "hide_avatars_tip": "Don't display avatars next to user display names",