Enable expiring license banner

This commit fixes a regression I introduced, and sets the
default value for the expiring subscription message to true.

part of: https://gitlab.com/gitlab-org/growth/product/-/issues/102

app/views/layouts/_page.html.haml

@@ -5,7 +5,7 @@
     .mobile-overlay
     .alert-wrapper
       = render 'shared/outdated_browser'
-      - if Feature.enabled?(:subscribable_banner_license)
+      - if Feature.enabled?(:subscribable_banner_license, default_enabled: true)
         = render_if_exists "layouts/header/ee_subscribable_banner"
       = render "layouts/broadcast"
       = render "layouts/header/read_only_banner"

ee/changelogs/unreleased/jswain_enable_subscribable_banner.yml

+---
+title: Enable expiring subscription banner
+merge_request: 30304
+author:
+type: added