tests: use User.lazy_create in data_setup

This lets us avoid the LDAP lookups in User.by_user_name (if LDAP is
enabled), which might be problematic for some test data.

Change-Id: I078f6a5d9a3e2ba7a16a9c3d74fc935999a947d7
Merge "tests: use User.lazy_create in data_setup" into develop