Combine examples to reduce factories in specs (#33841)

spec/controllers/relationships_controller_spec.rb

@@ -14,11 +14,9 @@ RSpec.describe RelationshipsController do
         get :show, params: { page: 2, relationship: 'followed_by' }
       end
 
-      it 'returns http success' do
+      it 'returns http success and private cache control headers' do
         expect(response).to have_http_status(200)
-      end
 
-      it 'returns private cache control headers' do
         expect(response.headers['Cache-Control']).to include('private, no-store')
       end
     end