Legacy license support for GitLab Duo

What does this MR do and why?

Self-managed instances can end up on a legacy license for a myriad of reasons. When visiting /admin/code_suggestions this is not an obvious problem because the empty state just encourages purchasing GitLab Duo seats, which may not be reasonable or relevant.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Click to expand

How to set up and validate locally

• Apply patch:

diff --git a/ee/app/graphql/resolvers/admin/cloud_licenses/current_license_resolver.rb b/ee/app/graphql/resolvers/admin/cloud_licenses/current_license_resolver.rb
index f2cb629500e4..0146a63641ff 100644
--- a/ee/app/graphql/resolvers/admin/cloud_licenses/current_license_resolver.rb
+++ b/ee/app/graphql/resolvers/admin/cloud_licenses/current_license_resolver.rb
@@ -10,6 +10,25 @@ class CurrentLicenseResolver < BaseResolver
         type ::Types::Admin::CloudLicenses::CurrentLicenseType, null: true
 
         def resolve
+          return OpenStruct.new(
+            id: '1',
+            plan: 'ultimate',
+            license_type: 'legacy_license',
+            licensee_name: 'name',
+            licensee_email: 'email',
+            licensee_company: 'company',
+            starts_at: 1.day.ago,
+            created_at: 1.day.ago,
+            expires_at: 1.year.from_now,
+            block_changes_at: 1.year.from_now,
+            activated_at: 1.day.ago,
+            restricted_user_count: 10,
+            last_synced_at: 1.day.ago,
+            daily_billable_users_count: 10,
+            maximum_user_count: 100,
+            overage_with_historical_max: 100,
+            trial?: false
+          )
           authorize!
 
           license
diff --git a/ee/app/models/license.rb b/ee/app/models/license.rb
index aac4ae494b56..87e2fa8b7f8b 100644
--- a/ee/app/models/license.rb
+++ b/ee/app/models/license.rb
@@ -56,6 +56,7 @@ class License < ApplicationRecord
 
   class << self
     def current
+      return ::OpenStruct.new(starts_at: 1.year.ago, expires_at: 1.year.from_now, paid?: true)
       cache.fetch(CACHE_KEY, as: License, expires_in: 1.minute) { load_license }
     end
 
@@ -77,6 +78,7 @@ def block_changes?
     end
 
     def feature_available?(feature)
+      return true
       # Include features available per plan + usage ping features if Usage Pings is enabled
       # as instance setting.
       !!current&.feature_available?(feature) ||

mypatch.patch

• or apply license following these docs: https://docs.gitlab.com/ee/development/ai_features/index.html#option-b-run-gdk-in-self-managed-mode-and-enable-ai-features-for-the-instance
• Export this environment variable export GITLAB_SIMULATE_SAAS=0 and restart GDK.
• Sign in as admin. Visit /admin/code_suggestions.

Related to #473402