Revert "Default puma to running on localhost only." (#8444)

* Revert "Default puma to running on localhost only. (#8429)"

This reverts commit 2a59c6a5e7.

config/puma.rb

@@ -4,8 +4,7 @@ threads threads_count, threads_count
 if ENV['SOCKET'] then
   bind 'unix://' + ENV['SOCKET']
 else
-  port_num = ENV.fetch('PORT') { 3000 }
-  bind "tcp://127.0.0.1:#{port_num}"
+  port ENV.fetch('PORT') { 3000 }
 end
 
 environment ENV.fetch('RAILS_ENV') { 'development' }