[6.x] Add 'null' logging channel (#5106)

* Add 'none' logging channel

* Remove extra spaces

* Rename 'none' channel to 'null'

* Update logging.php

config/logging.php

@@ -1,5 +1,6 @@
 <?php
 
+use Monolog\Handler\NullHandler;
 use Monolog\Handler\StreamHandler;
 use Monolog\Handler\SyslogUdpHandler;
 
@@ -89,6 +90,11 @@ return [
             'driver' => 'errorlog',
             'level' => 'debug',
         ],
+
+        'null' => [
+            'driver' => 'monolog',
+            'handler' => NullHandler::class,
+        ],
     ],
 
 ];