Enable the feature flag by default

NuGet uploads are now processed by the new package file updater. This
fixes issues with large packages.

See the details in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/66728

Changelog: fixed

config/feature_flags/development/packages_nuget_new_package_file_updater.yml

@@ -2,7 +2,7 @@
 name: packages_nuget_new_package_file_updater
 introduced_by_url:
 rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/336511
-milestone: '14.1'
+milestone: '14.2'
 type: development
 group: group::package
-default_enabled: false
+default_enabled: true