Merge branch '3.4' into 4.3

* 3.4:
  cleanups
  Disable PHPUnit result cache on the CI
  [Translation] Highlight invalid translation status

Author: nicolas-grekas

Tests/Compiler/ValidateEnvPlaceholdersPassTest.php

@@ -282,7 +282,6 @@ public function testEmptyConfigFromMoreThanOneSource()
         $container = new ContainerBuilder();
         $container->registerExtension(new EnvExtension(new ConfigurationWithArrayNodeRequiringOneElement()));
         $container->loadFromExtension('env_extension', []);
-        $container->loadFromExtension('env_extension', []);
 
         $this->doProcess($container);