This property shouldn't be needed in modern code, where most things can
use Authority. So much so because TestUser adds a dependency on the
database, but many tests that use TestUser don't even need the database.
ApiTestCase, in particular, sets this property in setUp, thus adding a
database dependency to all API tests, including those that don't need
users or the database at all.
Deprecate the property and replace existing usages in core. The one in
ApiTestCase is much harder to migrate, but this patch replaces the array
with an anonymous ArrayAccess class to allow lazy initialization and
remove DB dependencies.
Bug: T155147
Change-Id: I59c4ed1f6a7572d3a92387b15b8e56625bc376a2
4c72c161d8