Do not exclude spec_helper.rb from Rails/I18nLocaleAssignment cop

Use the around action to set the desired locale so we do not break the rule.

.rubocop.yml

@@ -269,8 +269,6 @@ Rails/HttpStatus:
 
 Rails/I18nLocaleAssignment:
   Enabled: true
-  Exclude:
-    - "spec/spec_helper.rb"
 
 Rails/InverseOf:
   Enabled: true

spec/spec_helper.rb

@@ -30,11 +30,16 @@ RSpec.configure do |config|
   end
 
   config.before do |example|
-    I18n.locale = :en
     Globalize.set_fallbacks_to_all_available_locales
     Setting["feature.user.skip_verification"] = nil
   end
 
+  config.around do |example|
+    I18n.with_locale(:en) do
+      example.run
+    end
+  end
+
   config.around(:each, :race_condition) do |example|
     self.use_transactional_tests = false
     example.run