chore(config): private constructor for managed rule identifiers class (…

…#10859)

lost this change unintentionally during a merge.

introducing it so there isn't a default constructor as this class is not
intended to be instantiated.


----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-config/lib/rule.ts

@@ -1259,6 +1259,9 @@ export class ManagedRuleIdentifiers {
    * @see https://docs.aws.amazon.com/config/latest/developerguide/wafv2-logging-enabled.html
    */
   public static readonly WAFV2_LOGGING_ENABLED = 'WAFV2_LOGGING_ENABLED';
+
+  // utility class
+  private constructor() { }
 }
 
 /**