Drop support for /cache/tag.json.

Drop support for https://danbooru.donmai.us/cache/tags.json. This was a
nightly dump of the tags table that was originally added in #1012. It
was never documented and never really used except for by the DanbooruUp
extension.

app/logical/api_cache_generator.rb

@@ -1,33 +0,0 @@
-# donmai.us specific
-
-class ApiCacheGenerator
-  def generate_tag_cache
-    path = Danbooru.config.shared_dir_path
-    FileUtils.mkdir_p("#{path}/system/cache")
-    File.open("#{path}/system/cache/tags.json", "w") do |f|
-      f.print("[")
-      Tag.without_timeout do
-        Tag.find_each do |tag|
-          next unless tag.post_count > 0
-          hash = {
-            "name" => tag.name,
-            "id" => tag.id,
-            "created_at" => tag.created_at,
-            "post_count" => tag.post_count,
-            "category" => tag.category
-          }
-          f.print(hash.to_json)
-          f.print(", ")
-        end
-      end
-      f.seek(-2, IO::SEEK_END)
-      f.print("]\n")
-    end
-    Zlib::GzipWriter.open("#{path}/system/cache/tags.json.gz") do |gz|
-      gz.write(IO.binread("#{path}/system/cache/tags.json"))
-      gz.close
-    end
-    RemoteFileManager.new("#{path}/system/cache/tags.json").distribute
-    RemoteFileManager.new("#{path}/system/cache/tags.json.gz").distribute
-  end
-end

app/logical/danbooru_maintenance.rb

@@ -13,7 +13,6 @@ module DanbooruMaintenance
     Delayed::Job.where('created_at < ?', 45.days.ago).delete_all
     PostVote.prune!
     CommentVote.prune!
-    ApiCacheGenerator.new.generate_tag_cache
     PostDisapproval.prune!
     ForumSubscription.process_all!
     TagAlias.update_cached_post_counts_for_all

app/logical/remote_file_manager.rb

@@ -1,54 +0,0 @@
-require 'securerandom'
-
-class RemoteFileManager
-  attr_reader :path
-
-  def initialize(path)
-    @path = path
-  end
-
-  def distribute_to_archive(dest_url)
-    uri = URI.parse(dest_url)
-    dir_name = uri.host.split(".").first
-    uuid = SecureRandom.uuid
-    dest_path = "/var/www/#{dir_name}#{uri.path}"
-    temp_path = "/tmp/rfm-#{Danbooru.config.server_host}-#{uuid}"
-    
-    Net::SFTP.start(uri.host, Danbooru.config.archive_server_login) do |ftp|
-      ftp.upload!(path, temp_path)
-      begin
-        ftp.rename!(temp_path, dest_path)
-      rescue Net::SFTP::StatusException
-        ftp.remove!(dest_path)
-        ftp.rename!(temp_apth, dest_path)
-      end
-    end
-  end
-
-  def distribute
-    uuid = SecureRandom.uuid
-    temp_path = "/tmp/rfm-#{Danbooru.config.server_host}-#{uuid}"
-
-    Danbooru.config.other_server_hosts.each do |hostname|
-      Net::SFTP.start(hostname, Danbooru.config.remote_server_login) do |ftp|
-        ftp.upload!(path, temp_path)
-        begin
-          ftp.rename!(temp_path, path)
-        rescue Net::SFTP::StatusException
-          # this typically means the file already exists
-          # so delete and try renaming again
-          ftp.remove!(path)
-          ftp.rename!(temp_path, path)
-        end
-      end
-    end
-  end
-
-  def delete
-    Danbooru.config.other_server_hosts.each do |hostname|
-      Net::SFTP.start(hostname, Danbooru.config.remote_server_login) do |ftp|
-        ftp.remove(path)
-      end
-    end
-  end
-end