Add new "performance" data to auth

To fill out performance data that we added for stock management, we need to add some users to reference data, which means we need to add corresponding users in auth.

For demo data loading, we're moving away from our JSON approach to the TestDataInitializer, in order to use CSVs.

Acceptance Criteria

• All auth demo data is now using TestDataInitializer and associated code (copy from stock management) to load demo data (Spring profile "demo-data", not "performance-data")

• New auth users CSV is added (use CSV attached)

• Old demo data approach should be "cleaned up" (no /demo-data folder, or demoDataSeed task)