Add custom header text to free personal namespaces billing page

 - add text

ee/app/helpers/billing_plans_helper.rb

@@ -131,6 +131,10 @@ def show_start_free_trial_messages?(namespace)
     !free_personal_namespace?(namespace) && namespace.eligible_for_trial?
   end
+  def show_group_billing_ctas?(namespace)
+    free_personal_namespace?(namespace)
+  end
+
   private
   def add_seats_url(group)

ee/app/views/shared/billings/_trial_status.html.haml

 - faq_link          = link_to s_("BillingPlans|frequently asked questions"), "https://about.gitlab.com/gitlab-com/#faq"
 - pricing_page_link = link_to s_("BillingPlans|Pricing page"), "https://about.gitlab.com/pricing"
+- groups_link = link_to s_("BillingPlans|group"), dashboard_groups_path
 - show_start_free_trial_messages = show_start_free_trial_messages?(namespace)
+- show_group_billing_ctas = show_group_billing_ctas?(namespace)
 - if show_start_free_trial_messages
   = html_escape(s_("BillingPlans|Learn more about each plan by reading our %{faq_link}, or start a free 30-day trial of GitLab.com Ultimate.")) % { faq_link: faq_link.html_safe }
@@ -8,5 +10,7 @@
   = html_escape(s_("BillingPlans|Your GitLab.com %{plan} trial will %{strong_open}expire after %{expiration_date}%{strong_close}. You can retain access to the %{plan} features by upgrading below.")) % { plan: namespace.gitlab_subscription&.plan_title, expiration_date: namespace.trial_ends_on, strong_open: '<strong>'.html_safe, strong_close: '</strong>'.html_safe }
 - elsif namespace.trial_expired? && namespace.free_plan?
   = s_("BillingPlans|Your GitLab.com trial expired on %{expiration_date}. You can restore access to the features at any time by upgrading below.") % { expiration_date: namespace.trial_ends_on }
+- elsif show_group_billing_ctas
+  = html_escape(s_("BillingPlans|Looking to purchase or manage a subscription for your group? Navigate to your %{groups_link} and go to %{strong_open}Settings > Billing.%{strong_close}")) % { groups_link: groups_link.html_safe, strong_open: '<strong>'.html_safe, strong_close: '</strong>'.html_safe }
 - else
   = html_escape(s_("BillingPlans|Learn more about each plan by visiting our %{pricing_page_link}.")) % { pricing_page_link: pricing_page_link.html_safe }