Allow non-group Agent projects to authorize themselves

Changelog: fixed

app/services/clusters/agents/refresh_authorization_service.rb

@@ -86,7 +86,7 @@ module Clusters
         if group_root_ancestor?
           root_ancestor.all_projects
         else
-          ::Project.none
+          ::Project.id_in(project.id)
         end
       end
 

spec/services/clusters/agents/refresh_authorization_service_spec.rb

@@ -113,6 +113,16 @@ RSpec.describe Clusters::Agents::RefreshAuthorizationService do
         expect(modified_authorization.config).to eq({ 'default_namespace' => 'new-namespace' })
       end
 
+      context 'project does not belong to a group, and is authorizing itself' do
+        let(:root_ancestor) { create(:namespace) }
+        let(:added_project) { project }
+
+        it 'creates an authorization record for the project' do
+          expect(subject).to be_truthy
+          expect(agent.authorized_projects).to contain_exactly(added_project)
+        end
+      end
+
       context 'config contains too many projects' do
         before do
           stub_const("#{described_class}::AUTHORIZED_ENTITY_LIMIT", 1)