Inconsistent state with rest source and MP users

[mpgxvii]

• When a ManagementPortal user/subject is deleted, this is not deleted on the rest-sources-auth side which results in an inconsistent state
• So the Kafka connectors still end up trying to get the tokens for the rest source users, resulting in HttpException in the connector

[yatharthranjan]

Yes, a periodic clean up task on rest-sources auth would be good to sync state with MP.

Should the appserver do this too? Otherwise it might keep sending notifications to users that are deleted from the MP but still have the app installed?