Fixes technical debt issues for cluster domain

- Avoid using direct code on spec migration
- Removes milestone and point to issue, to avoid making fake promises

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/57397

app/models/clusters/cluster.rb

@@ -221,7 +221,8 @@ module Clusters
     # ProjectAutoDevops#Domain, project variables or group variables,
     # as the AUTO_DEVOPS_DOMAIN is needed for CI_ENVIRONMENT_URL
     #
-    # This method should be removed on 12.0
+    # This method should is scheduled to be removed on
+    # https://gitlab.com/gitlab-org/gitlab-ce/issues/56959
     def legacy_auto_devops_domain
       if project_type?
         project&.auto_devops&.domain.presence ||

app/models/project_auto_devops.rb

@@ -27,7 +27,8 @@ class ProjectAutoDevops < ActiveRecord::Base
   # From 11.8, AUTO_DEVOPS_DOMAIN has been replaced by KUBE_INGRESS_BASE_DOMAIN.
   # See Clusters::Cluster#predefined_variables and https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24580
   # for more info.
-  # Support for AUTO_DEVOPS_DOMAIN support will be dropped on 12.0 on
+  #
+  # Suppport AUTO_DEVOPS_DOMAIN is scheduled to be removed on
   # https://gitlab.com/gitlab-org/gitlab-ce/issues/52363
   def predefined_variables
     Gitlab::Ci::Variables::Collection.new.tap do |variables|

spec/migrations/migrate_auto_dev_ops_domain_to_cluster_domain_spec.rb

@@ -55,8 +55,8 @@ describe MigrateAutoDevOpsDomainToClusterDomain, :migration do
       expect(clusters_with_domain.count).to eq(20)
 
       project_auto_devops_with_domain.each do |project_auto_devops|
-        cluster_project = Clusters::Project.find_by(project_id: project_auto_devops.project_id)
-        cluster = Clusters::Cluster.find(cluster_project.cluster_id)
+        cluster_project = find_cluster_project(project_auto_devops.project_id)
+        cluster = find_cluster(cluster_project.cluster_id)
 
         expect(cluster.domain).to be_present
       end
@@ -64,8 +64,8 @@ describe MigrateAutoDevOpsDomainToClusterDomain, :migration do
       expect(clusters_without_domain.count).to eq(25)
 
       project_auto_devops_without_domain.each do |project_auto_devops|
-        cluster_project = Clusters::Project.find_by(project_id: project_auto_devops.project_id)
-        cluster = Clusters::Cluster.find(cluster_project.cluster_id)
+        cluster_project = find_cluster_project(project_auto_devops.project_id)
+        cluster = find_cluster(cluster_project.cluster_id)
 
         expect(cluster.domain).not_to be_present
       end
@@ -88,6 +88,14 @@ describe MigrateAutoDevOpsDomainToClusterDomain, :migration do
     end
   end
 
+  def find_cluster_project(project_id)
+    cluster_projects_table.where(project_id: project_id).first
+  end
+
+  def find_cluster(cluster_id)
+    clusters_table.where(id: cluster_id).first
+  end
+
   def project_auto_devops_with_domain
     project_auto_devops_table.where.not("domain IS NULL OR domain = ''")
   end