Indexer service throws IllegalArgumentException "User not provided for audit" when processing schema-worker requests from indexer-queue

Indexer-service (POST /schema-worker) is throwing IllegalArgumentException "User not provided for audit" when trying get headers.getUserEmail() and the value is not present in header. The requests are coming from indexer-queue service (based on SchemaChangedMessages). There is a proposal to add Service Principal to the request header authorization.

MR - !428 (merged)