Update the user-creation methods within the HudsonPrivateSecurityRealm class to make use of the user-creation listener methods of the SecurityListener class.

• To perform this update will require modifying the HudsonPrivateSecurityRealm class within the jenkins-core hudson/security package.
• Unit tests for the updated HudsonPrivateSecurityRealm class methods should be implemented, to verify their correctness, and should be added to the preexisting Jenkins unit tests for the HudsonPrivateSecurityRealm class.

The SecurityListener class methods related to listening for user-creation events were added in JENKINS-55305.