Fix Project.for_plan_name to use the correct plan

namespaces.plan_id is unused and we should be using the plan
from gitlab_subscriptions

ee/app/models/ee/project.rb

@@ -112,7 +112,7 @@ module EE
       scope :outside_shards, -> (shard_names) { where.not(repository_storage: Array(shard_names)) }
       scope :verification_failed_repos, -> { joins(:repository_state).merge(ProjectRepositoryState.verification_failed_repos) }
       scope :verification_failed_wikis, -> { joins(:repository_state).merge(ProjectRepositoryState.verification_failed_wikis) }
-      scope :for_plan_name, -> (name) { joins(namespace: :plan).where(plans: { name: name }) }
+      scope :for_plan_name, -> (name) { joins(namespace: { gitlab_subscription: :hosted_plan }).where(plans: { name: name }) }
       scope :requiring_code_owner_approval,
             -> { joins(:protected_branches).where(protected_branches: { code_owner_approval_required: true }) }
       scope :with_active_services, -> { joins(:services).merge(::Service.active) }

ee/spec/finders/ee/projects_finder_spec.rb

@@ -4,18 +4,19 @@ require 'spec_helper'
 
 describe ProjectsFinder do
   describe '#execute' do
+    let_it_be(:user) { create(:user) }
     let(:finder) { described_class.new(current_user: user, params: params, project_ids_relation: project_ids_relation) }
-    let(:user) { create(:user) }
 
     subject { finder.execute }
 
     describe 'filter by plans' do
       let(:params) { { plans: plans } }
       let(:project_ids_relation) { nil }
-      let!(:gold_project) { create_project(:gold_plan) }
-      let!(:gold_project2) { create_project(:gold_plan) }
-      let!(:silver_project) { create_project(:silver_plan) }
-      let!(:no_plan_project) { create_project(nil) }
+
+      let_it_be(:gold_project) { create_project(:gold_plan) }
+      let_it_be(:gold_project2) { create_project(:gold_plan) }
+      let_it_be(:silver_project) { create_project(:silver_plan) }
+      let_it_be(:no_plan_project) { create_project(nil) }
 
       context 'with gold plan' do
         let(:plans) { ['gold'] }
@@ -50,10 +51,7 @@ describe ProjectsFinder do
       private
 
       def create_project(plan)
-        namespace = create(:namespace_with_plan, plan: plan)
-        namespace.update(plan: namespace.gitlab_subscription&.hosted_plan)
-
-        create(:project, :public, namespace: namespace)
+        create(:project, :public, namespace: create(:namespace_with_plan, plan: plan))
       end
     end
   end