refactor: remove some outdated todos and legacy fallbacks

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mobilizon/discussions/discussions.ex

@@ -77,7 +77,7 @@ defmodule Mobilizon.Discussions do
     |> join(:left, [c], r in Comment, on: r.origin_comment_id == c.id)
     |> where([c, _], is_nil(c.in_reply_to_comment_id))
     |> where([c], c.visibility in ^@public_visibility)
-    # TODO: This was added because we don't want to count deleted comments in total_replies.
+    # This was added because we don't want to count deleted comments in total_replies.
     # However, it also excludes all top-level comments with deleted replies from being selected
     # |> where([_, r], is_nil(r.deleted_at))
     |> group_by([c], c.id)