Revert "reset Event System in TestRequest"

This reverts commit d09a8e055b.

We have test that manipulate the event handler (eg. registering their
own events on that handler) which broke with above commit.

A better way needs to be found.

_test/core/TestRequest.php

@@ -4,7 +4,6 @@
  * runtime inspection.
  */
 
-use dokuwiki\Extension\EventHandler;
 use dokuwiki\Input\Input;
 
 /**
@@ -149,10 +148,6 @@ class TestRequest {
         $_POST = $this->post;
         $_REQUEST = array_merge($_GET, $_POST);
 
-        // reset event handler
-        global $EVENT_HANDLER;
-        $EVENT_HANDLER = new EventHandler();
-
         // reset output buffer
         $this->output_buffer = '';