FOSS master broken: The feature flag YAML definition for 'invite_members_new_dropdown_experiment_percentage' does not exist

On the latest merge to FOSS master gitlab-foss@f368b496, we have some legit failures

  21) Branches (JavaScript fixtures) Projects::BranchesController (JavaScript fixtures) branches/new_branch.html
      Failure/Error: raise exception if should_raise_for_dev?
      Feature::InvalidFeatureFlagError:
        The feature flag YAML definition for 'invite_members_new_dropdown_experiment_percentage' does not exist
      # ./lib/gitlab/error_tracking.rb:87:in `track_and_raise_for_dev_exception'
      # ./lib/feature/definition.rb:123:in `default_enabled?'
      # ./lib/feature.rb:72:in `enabled?'
      # ./spec/support/helpers/stubbed_feature.rb:41:in `enabled?'
      # ./lib/gitlab/experimentation/experiment.rb:19:in `active?'
      # ./lib/gitlab/experimentation.rb:119:in `active?'
      # ./app/views/layouts/header/_project_invite_members_new_dropdown_item.html.haml:1:in `_app_views_layouts_header__project_invite_members_new_dropdown_item_html_haml__4158358197610112927_305480'
      # ./app/views/layouts/header/_new_dropdown.haml:37:in `_app_views_layouts_header__new_dropdown_haml__2263380184811285910_304340'
      # ./app/views/layouts/header/_default.html.haml:30:in `_app_views_layouts_header__default_html_haml___2355499736535133158_304140'
      # ./app/views/layouts/application.html.haml:12:in `_app_views_layouts_application_html_haml___2049245812686251388_303940'
      # ./app/views/layouts/project.html.haml:16:in `_app_views_layouts_project_html_haml___661929729250045235_303900'

See https://gitlab.com/gitlab-org/gitlab-foss/-/jobs/945507694

These failures are not present on GitLab master canonical but they're present on GitLab masterSecurity (which is blocking the automatic merging on security fixes at the moment), see https://gitlab.com/gitlab-org/security/gitlab/-/jobs/945632772 as example