Resolved enabled extension test

The getEnabled method returns all extensions (previously) enabled, yet manually
uninstalled through composer. This does not reference the exact, current state
of the forum. getEnabledExtensions returns a list where the getEnabled list
is filtered on the extensions found in the composer installed.json file.

src/Extension/ExtensionManager.php

@@ -316,7 +316,7 @@ class ExtensionManager
      */
     public function isEnabled($extension)
     {
-        return in_array($extension, $this->getEnabled());
+        return in_array($extension, $this->getEnabledExtensions());
     }
 
     /**