Use RAILS_LOG_LEVEL to set log level of Sidekiq, too (#7079)

Fix #3565 (oops)

config/initializers/sidekiq.rb

 # frozen_string_literal: true
 
-namespace = ENV.fetch('REDIS_NAMESPACE') { nil }
+namespace    = ENV.fetch('REDIS_NAMESPACE') { nil }
 redis_params = { url: ENV['REDIS_URL'] }
 
 if namespace
-  redis_params [:namespace] = namespace
+  redis_params[:namespace] = namespace
 end
 
 Sidekiq.configure_server do |config|
@@ -18,3 +18,5 @@ end
 Sidekiq.configure_client do |config|
   config.redis = redis_params
 end
+
+Sidekiq::Logging.logger.level = ::Logger::const_get(ENV.fetch('RAILS_LOG_LEVEL', 'info').upcase.to_s)