Remove unused failure action in api/base controller spec (#32905)

spec/controllers/api/base_controller_spec.rb

@@ -7,10 +7,6 @@ RSpec.describe Api::BaseController do
     def success
       head 200
     end
-
-    def failure
-      FakeService.new
-    end
   end
 
   it 'returns private cache control headers by default' do