Enabling nuget_package_registry feature flag by default

See the epic https://gitlab.com/groups/gitlab-org/-/epics/2271

ee/changelogs/unreleased/10io-remove-nuget-feature-flag.yml

+---
+title: Add NuGet Repository
+merge_request: 25157
+author:
+type: added

ee/lib/api/nuget_packages.rb

@@ -90,7 +90,7 @@ module API
     end
     resource :projects, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
       before do
-        not_found! if Feature.disabled?(:nuget_package_registry, authorized_user_project)
+        not_found! if Feature.disabled?(:nuget_package_registry, authorized_user_project, default_enabled: true)
         authorize_packages_feature!(authorized_user_project)
       end