chore: Minor Housekeeping tasks (#3169)

- Limit Rack attack to production environments
- Make the long-running data migration optional

db/migrate/20210923190418_add_online_status_to_account_users.rb

@@ -4,12 +4,9 @@ class AddOnlineStatusToAccountUsers < ActiveRecord::Migration[6.1]
       t.integer :availability, default: 0, null: false
       t.boolean :auto_offline, default: true, null: false
     end
-
-    update_existing_user_availability
   end
 
-  private
-
+  # run as a seperate data migration if you want to migrate the user statuses
   def update_existing_user_availability
     User.find_in_batches do |user_batch|
       user_batch.each do |user|