Symfony version(s) affected: 4.3.3+ 9a2fcc9

Description
When running the HttpCache kernel with debug option false and no explicit trace_level, the default does not get initialized. The kernel still unconditionally calls addTraces.

How to reproduce
https://github.com/FriendsOfSymfony/FOSHttpCache/blob/master/tests/Unit/SymfonyCache/EventDispatchingHttpCacheTest.php
https://travis-ci.org/FriendsOfSymfony/FOSHttpCache/jobs/565046971

Possible Solution
Change this

   if (!isset($options['trace_level'])) {
            $this->options['trace_level'] =  $this->options['debug'] ? 'full' : 'none';
   }

That code would actually match with the documentation on the parameter: "(default: 'full' if in debug; 'none' otherwise)"

Happy to write a pull request if you agree that this would be correct.