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

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

app/ring_groups/resources/classes/ring_groups.php

@@ -62,16 +62,6 @@ if (!class_exists('ring_groups')) {
 
 		}
 
-		/**
-		 * 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);
-			}
-		}
-
 		/**
 		 * delete records
 		 */