Revert "Add handler for Move activity (#9629)"

This reverts commit 0f938ff29c.

app/models/account.rb

@@ -44,7 +44,6 @@
 #  fields                  :jsonb
 #  actor_type              :string
 #  discoverable            :boolean
-#  also_known_as           :string           is an Array
 #
 
 class Account < ApplicationRecord
@@ -233,10 +232,6 @@ class Account < ApplicationRecord
     end
   end
 
-  def also_known_as
-    self[:also_known_as] || []
-  end
-
   def fields
     (self[:fields] || []).map { |f| Field.new(self, f) }
   end