remove unneeded destruct methods as GC has higher performance (#6631)

Co-authored-by: Tim Fry <tim@voipstratus.com>

resources/classes/config.php

@@ -30,16 +30,6 @@ class config {
 		//place holder
 	}
 
-	/**
-	 * Called when there are no references to a particular object
-	 * unset the variables used in the class
-	 */
-	public function __destruct() {
-		foreach ($this as $key => $value) {
-			unset($this->$key);
-		}
-	}
-
 	/**
 	 * Determine whether the config.php exists
 	 * @var string $db_type - type of database