Fix stoplight not using REDIS_NAMESPACE (#18160)

config/initializers/stoplight.rb

 require 'stoplight'
 
-Stoplight::Light.default_data_store = Stoplight::DataStore::Redis.new(Redis.current)
+Stoplight::Light.default_data_store = Stoplight::DataStore::Redis.new(RedisConfiguration.new.connection)
 Stoplight::Light.default_notifiers  = [Stoplight::Notifier::Logger.new(Rails.logger)]