revert disabling DebugHandler in CLI environments

As the cache is shared between the different server APIs, the debug
handler needs to take care of abstaining itself.

Author: xabbuh

DependencyInjection/Compiler/DebugHandlerPass.php

@@ -46,11 +46,6 @@ public function process(ContainerBuilder $container)
             return;
         }
 
-        // disable the DebugHandler in CLI as it tends to leak memory if people enable kernel.debug
-        if ('cli' === PHP_SAPI) {
-            return;
-        }
-
         $debugHandler = new Definition('%monolog.handler.debug.class%', array(Logger::DEBUG, true));
         $container->setDefinition('monolog.handler.debug', $debugHandler);