searchable: refactor searchable_includes.

Pass searchable associations directly to search_attributes instead of
defining them separately in searchable_includes.

app/models/comment_vote.rb

@@ -19,7 +19,7 @@ class CommentVote < ApplicationRecord
   end
 
   def self.search(params)
-    q = search_attributes(params, :id, :created_at, :updated_at, :score)
+    q = search_attributes(params, :id, :created_at, :updated_at, :score, :comment, :user)
     q.apply_default_order(params)
   end
 
@@ -37,10 +37,6 @@ class CommentVote < ApplicationRecord
     score == -1
   end
 
-  def self.searchable_includes
-    [:comment, :user]
-  end
-
   def self.available_includes
     [:comment, :user]
   end