Change railties default log_level to :error

The default of :info generates a ton of unnecessary noise in the railties logs.

railties/test/application/configuration_test.rb

@@ -89,6 +89,7 @@ module ApplicationTests
     def restore_default_config
       FileUtils.rm_rf("#{app_path}/config/environments")
       FileUtils.mv("#{app_path}/config/__environments__", "#{app_path}/config/environments")
+      remove_from_env_config "production", "config.log_level = :error"
     end
 
     test "Rails.env does not set the RAILS_ENV environment variable which would leak out into rake tasks" do

railties/test/isolation/abstract_unit.rb

@@ -145,6 +145,7 @@ module TestHelpers
       add_to_env_config :development, "config.action_view.annotate_rendered_view_with_filenames = false"
 
       remove_from_env_config("development", "config.generators.apply_rubocop_autocorrect_after_generate!")
+      add_to_env_config :production, "config.log_level = :error"
     end
 
     def teardown_app
@@ -262,7 +263,7 @@ module TestHelpers
       @app.config.eager_load = false
       @app.config.session_store :cookie_store, key: "_myapp_session"
       @app.config.active_support.deprecation = :log
-      @app.config.log_level = :info
+      @app.config.log_level = :error
       @app.config.secret_key_base = "b3c631c314c0bbca50c1b2843150fe33"
 
       yield @app if block_given?