Removed invalid call that shouldn't be used anyway

Is intended for testing only anyway

Author: rhukster

src/DebugBar/Bridge/Twig/TraceableTwigTemplate.php

@@ -118,9 +118,4 @@ public function render(array $context)
 
         return ob_get_clean();
     }
-
-    public static function clearCache()
-    {
-        $this->template->clearCache();
-    }
 }