Don't warn or use Gemfile.extra when not using engine_cart (#4962)

* Don't warn or use Gemfile.extra when not using engine_cart

* Appease rubocop

* Appease rubocop

Gemfile

@@ -19,26 +19,18 @@ test_app_path = ENV['RAILS_ROOT'] ||
                 ENV.fetch('ENGINE_CART_DESTINATION', File.expand_path('.internal_test_app', File.dirname(__FILE__)))
 test_app_gemfile = File.expand_path('Gemfile', test_app_path)
 
+# rubocop:disable Bundler/DuplicatedGem
 if File.exist?(test_app_gemfile)
   begin
     eval_gemfile test_app_gemfile
   rescue Bundler::GemfileError => e
     Bundler.ui.warn '[Hyrax] Skipping Rails application dependencies:'
     Bundler.ui.warn e.message
   end
-else
-  Bundler.ui.warn "[Hyrax] Unable to find test application dependencies in #{test_app_gemfile}, using placeholder dependencies"
-
-  # rubocop:disable Bundler/DuplicatedGem
-  if ENV['RAILS_VERSION']
-    if ENV['RAILS_VERSION'] == 'edge'
-      gem 'rails', github: 'rails/rails', source: 'https://rubygems.org'
-      ENV['ENGINE_CART_RAILS_OPTIONS'] = '--edge --skip-turbolinks'
-    else
-      gem 'rails', ENV['RAILS_VERSION'], source: 'https://rubygems.org'
-    end
-  end
-  # rubocop:enable Bundler/DuplicatedGem
-
-  eval_gemfile File.expand_path('spec/test_app_templates/Gemfile.extra', File.dirname(__FILE__))
+elsif ENV['RAILS_VERSION'] == 'edge'
+  gem 'rails', github: 'rails/rails', source: 'https://rubygems.org'
+  ENV['ENGINE_CART_RAILS_OPTIONS'] = '--edge --skip-turbolinks'
+elsif ENV['RAILS_VERSION']
+  gem 'rails', ENV['RAILS_VERSION'], source: 'https://rubygems.org'
 end
+# rubocop:enable Bundler/DuplicatedGem