tests: adapt auth-tests to files provider
Let's take advantage of the files provider and start to get rid of the
local provider references in our code.
Apart from the obvious change from "local" to "files" and from "LOCAL"
to "FILES", we also had to change the cleanup function as this test
suite doesn't rely on test_multidom_suite_cleanup().
Related:
https://pagure.io/SSSD/sssd/issue/3304
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
Reviewed-by: Pavel Březina <pbrezina@redhat.com>