remove rack attack middleware update
Created by: bbodenmiller
Hasn't changed since 7.2 release: https://github.com/gitlabhq/gitlabhq/commits/master/config/initializers/rack_attack.rb.example
Created by: bbodenmiller
Hasn't changed since 7.2 release: https://github.com/gitlabhq/gitlabhq/commits/master/config/initializers/rack_attack.rb.example