chore: Removing duplicate callback to create auth token (#2624)

Removed after create callback in user model to create a new access token. This is already being taken care of by AccessTokenable module.

Fixes #2620

db/migrate/20210714110714_remove_duplicate_access_tokens_for_existing_users.rb

@@ -0,0 +1,12 @@
+class RemoveDuplicateAccessTokensForExistingUsers < ActiveRecord::Migration[6.0]
+  def up
+    # find all models and group them on owner
+    grouped_tokens = AccessToken.all.group_by(&:owner)
+    grouped_tokens.each_value do |duplicates|
+      # we want to keep the latest token as it is being used in all requests
+      duplicates.pop
+      # Remaining ones are duplicates, delete them all
+      duplicates.each { |duplicate| AccessToken.find_by(id: duplicate).destroy }
+    end
+  end
+end