Fetch Ultimate plan ID from CustomersDot for trial prompts

- `TrialStatusWidgetHelper#ultimate_plan_id`
- `PaidFeatureCalloutHelper#premium_plan_id`
- Use the `GitlabSubscription::FetchSubscriptionPlansService` for each
  of those cases

Note: The `PaidFeatureCalloutHelper` is part of an experiment which is
currently unreachable
(https://gitlab.com/gitlab-org/gitlab/-/issues/273627#note_674150108)
but is yet to be cleaned up. It is likely that the code for it will be
entirely removed. If not, there is already an issue in place to extract
the commonalities between these two helpers
(https://gitlab.com/gitlab-org/gitlab/-/issues/340441), including
reusing the `FetchSubscriptionPlansService` data:
https://gitlab.com/gitlab-org/gitlab/-/blob/8938a54040c52454f58562626bf38584462f75c0/ee/app/helpers/trial_upgrade_prompts_helper.rb#L35

ee/app/helpers/paid_feature_callout_helper.rb

@@ -48,14 +48,16 @@ module PaidFeatureCalloutHelper
   end
 
   def premium_subscription_path_for_group(group)
-    # NOTE: We are okay hard-coding the production value for the Premium 1-year
-    # SaaS plan ID while this is all part of an active experiment. If & when the
-    # experiment is deemed a success, part of the clean-up effort will be to
-    # pull the value directly from the CustomersDot API. Value taken from
-    # https://gitlab.com/gitlab-org/customers-gitlab-com/blob/7177f13c478ef623b779d6635c4a58ee650b7884/config/application.yml#L186
-    # Cleanup issue: https://gitlab.com/gitlab-org/gitlab/-/issues/330987
-    zuora_premium_plan_id = '2c92a00d76f0d5060176f2fb0a5029ff'
-
-    new_subscriptions_path(namespace_id: group.id, plan_id: zuora_premium_plan_id)
+    new_subscriptions_path(namespace_id: group.id, plan_id: premium_plan_id)
+  end
+
+  def premium_plan_id
+    strong_memoize(:premium_plan_id) do
+      plans = GitlabSubscriptions::FetchSubscriptionPlansService.new(plan: :free).execute
+
+      next unless plans
+
+      plans.find { |data| data['code'] == 'premium' }&.fetch('id', nil)
+    end
   end
 end

ee/app/helpers/trial_status_widget_helper.rb

@@ -11,13 +11,6 @@ module TrialStatusWidgetHelper
   D14_CALLOUT_ID = 'trial_status_reminder_d14'
   D3_CALLOUT_ID = 'trial_status_reminder_d3'
 
-  # NOTE: We are okay hard-coding the production value for the Ulitmate 1-year
-  # SaaS plan ID while this is all part of an active experiment. If & when the
-  # experiment is deemed a success, part of the clean-up effort will be to
-  # pull the value directly from the CustomersDot API. Value taken from
-  # https://gitlab.com/gitlab-org/customers-gitlab-com/blob/7177f13c478ef623b779d6635c4a58ee650b7884/config/application.yml#L207
-  ZUORA_ULTIMATE_PLAN_ID = '2c92a0ff76f0d5250176f2f8c86f305a'
-
   def trial_status_popover_data_attrs(group)
     base_attrs = trial_status_common_data_attrs(group)
     base_attrs.merge(
@@ -83,6 +76,16 @@ module TrialStatusWidgetHelper
   end
 
   def ultimate_subscription_path_for_group(group)
-    new_subscriptions_path(namespace_id: group.id, plan_id: ZUORA_ULTIMATE_PLAN_ID)
+    new_subscriptions_path(namespace_id: group.id, plan_id: ultimate_plan_id)
+  end
+
+  def ultimate_plan_id
+    strong_memoize(:ultimate_plan_id) do
+      plans = GitlabSubscriptions::FetchSubscriptionPlansService.new(plan: :free).execute
+
+      next unless plans
+
+      plans.find { |data| data['code'] == 'ultimate' }&.fetch('id', nil)
+    end
   end
 end

ee/spec/helpers/paid_feature_callout_helper_spec.rb

@@ -91,6 +91,14 @@ RSpec.describe PaidFeatureCalloutHelper do
     let(:subscription) { instance_double(GitlabSubscription, plan_title: 'Ultimate') }
     let(:group) { instance_double(Group, id: 123, to_param: 'test-group', trial_days_remaining: 12, gitlab_subscription: subscription) }
 
+    before do
+      allow_next_instance_of(GitlabSubscriptions::FetchSubscriptionPlansService, plan: :free) do |instance|
+        allow(instance).to receive(:execute).and_return([
+          { 'code' => 'premium', 'id' => 'premium-plan-id' }
+        ])
+      end
+    end
+
     subject { helper.paid_feature_popover_data_attrs(group: group, feature_name: 'first feature') }
 
     it 'returns the set of data attributes needed to bootstrap the PaidFeatureCalloutPopover component' do
@@ -99,7 +107,7 @@ RSpec.describe PaidFeatureCalloutHelper do
         days_remaining: 12,
         feature_name: 'first feature',
         href_compare_plans: '/groups/test-group/-/billings',
-        href_upgrade_to_paid: '/-/subscriptions/new?namespace_id=123&plan_id=2c92a00d76f0d5060176f2fb0a5029ff',
+        href_upgrade_to_paid: '/-/subscriptions/new?namespace_id=123&plan_id=premium-plan-id',
         plan_name_for_trial: 'Ultimate',
         plan_name_for_upgrade: 'Premium',
         target_id: 'first-feature-callout'

ee/spec/helpers/trial_status_widget_helper_spec.rb

@@ -30,6 +30,11 @@ RSpec.describe TrialStatusWidgetHelper do
         trial_ends_on: trial_end_date
       )
       stub_experiments(forcibly_show_trial_status_popover: :candidate)
+      allow_next_instance_of(GitlabSubscriptions::FetchSubscriptionPlansService, plan: :free) do |instance|
+        allow(instance).to receive(:execute).and_return([
+          { 'code' => 'ultimate', 'id' => 'ultimate-plan-id' }
+        ])
+      end
     end
 
     after do
@@ -59,7 +64,7 @@ RSpec.describe TrialStatusWidgetHelper do
           expect(data_attrs).to match(
             shared_expected_attrs.merge(
               group_name: group.name,
-              purchase_href: new_subscriptions_path(namespace_id: group.id, plan_id: described_class::ZUORA_ULTIMATE_PLAN_ID),
+              purchase_href: new_subscriptions_path(namespace_id: group.id, plan_id: 'ultimate-plan-id'),
               target_id: shared_expected_attrs[:container_id],
               start_initially_shown: start_initially_shown,
               trial_end_date: trial_end_date,