Move override_rails_constants.rb to another location

We move override_rails_constants.rb to another location so that it's
closer to its related code in metrics_server.
We also remove the usage in setup-test-env as they differ in usage, and
reusing the code does not make a lot of sense.

scripts/override_rails_constants.rb → metrics_server/override_rails_constants.rb

@@ -3,12 +3,12 @@
 
 require 'active_support/environment_inquirer'
 
-module Rails # rubocop:disable Gitlab/NamespacedClass
+module Rails
   extend self
 
   def env
     @env ||= ActiveSupport::EnvironmentInquirer.new(
-      ENV["RAILS_ENV"].presence || ENV["RACK_ENV"].presence || "test"
+      ENV["RAILS_ENV"].presence || ENV["RACK_ENV"].presence || "development"
     )
   end
 

metrics_server/settings_overrides.rb

@@ -7,7 +7,7 @@
 # to all necessary constants. For example, we need Rails.root to
 # determine the location of bin/metrics-server.
 # Here we make the necessary constants available conditionally.
-require_relative '../scripts/override_rails_constants' unless Object.const_defined?('Rails')
+require_relative 'override_rails_constants' unless Object.const_defined?('Rails')
 
 require_relative '../config/settings'
 

scripts/setup-test-env

@@ -13,7 +13,17 @@ require 'active_support/string_inquirer'
 
 ENV['SKIP_RAILS_ENV_IN_RAKE'] = 'true'
 
-require_relative 'override_rails_constants'
+module Rails
+  extend self
+
+  def root
+    Pathname.new(File.expand_path('..', __dir__))
+  end
+
+  def env
+    @_env ||= ActiveSupport::StringInquirer.new(ENV["RAILS_ENV"] || ENV["RACK_ENV"] || "test")
+  end
+end
 
 ActiveSupport::Dependencies.autoload_paths << 'lib'