API: remove various associated fields included by default.

Remove various associated fields that were included by default on
certain endpoints. API users can use the only param to include the
full association if they need these fields.

* /artists.json: urls.
* /artist_urls.json: artist.
* /comments.json: creator_name and updater_name.
* /notes.json: creator_name.
* /pools.json: creator_name.
* /posts.json: uploader_name, children_ids, pixiv_ugoira_frame_data.
* /post_appeals.json: is_resolved.
* /post_versions.json: updater_name.
* /uploads.json: uploader_name.

app/models/post_appeal.rb

@@ -10,8 +10,6 @@ class PostAppeal < ApplicationRecord
   validate :validate_creator_is_not_limited
   validates_uniqueness_of :creator_id, :scope => :post_id, :message => "have already appealed this post"
 
-  api_attributes including: [:is_resolved]
-
   module SearchMethods
     def resolved
       joins(:post).where("posts.is_deleted = false and posts.is_flagged = false")