tests: fix unit tests.

* Move old post archive tests to post version tests.

* Fix pool tests that assumed that multiple edits by the same user
  weren't merged.

* Fix references to `is_active` and `notes` on artist model.

test/factories/comment_vote.rb

@@ -1,5 +1,6 @@
 FactoryBot.define do
   factory(:comment_vote) do
+    comment
     user
     score {1}
   end

test/factories/post.rb

@@ -1,6 +1,5 @@
 FactoryBot.define do
   factory(:post) do
-    created_at { 2.weeks.ago }
     sequence :md5 do |n|
       n.to_s
     end