Remove Salmon and PubSubHubbub (#11205)

* Remove Salmon and PubSubHubbub endpoints

* Add error when trying to follow OStatus accounts

* Fix new accounts not being created in ResolveAccountService

app/services/fetch_remote_account_service.rb

@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class FetchRemoteAccountService < BaseService
-  include AuthorExtractor
-
   def call(url, prefetched_body = nil, protocol = :ostatus)
     if prefetched_body.nil?
       resource_url, resource_options, protocol = FetchAtomService.new.call(url)
@@ -12,34 +10,8 @@ class FetchRemoteAccountService < BaseService
     end
 
     case protocol
-    when :ostatus
-      process_atom(resource_url, **resource_options)
     when :activitypub
       ActivityPub::FetchRemoteAccountService.new.call(resource_url, **resource_options)
     end
   end
-
-  private
-
-  def process_atom(url, prefetched_body:)
-    xml = Nokogiri::XML(prefetched_body)
-    xml.encoding = 'utf-8'
-
-    account = author_from_xml(xml.at_xpath('/xmlns:feed', xmlns: OStatus::TagManager::XMLNS), false)
-
-    UpdateRemoteProfileService.new.call(xml, account) if account.present? && trusted_domain?(url, account)
-
-    account
-  rescue TypeError
-    Rails.logger.debug "Unparseable URL given: #{url}"
-    nil
-  rescue Nokogiri::XML::XPath::SyntaxError
-    Rails.logger.debug 'Invalid XML or missing namespace'
-    nil
-  end
-
-  def trusted_domain?(url, account)
-    domain = Addressable::URI.parse(url).normalized_host
-    domain.casecmp(account.domain).zero? || domain.casecmp(Addressable::URI.parse(account.remote_url.presence || account.uri).normalized_host).zero?
-  end
 end