The `predefined_acl` test for `storage_object_acl` was failing. This is
because we removed the state-setting portion of the `predefined_acl`
field from `storage_bucket_acl`, and due to what I can only assume is a
copy/paste error, `storage_object_acl` was calling the Read function of
`storage_bucket_acl` instead of its own when using `predefined_acl`.
Updating to use `storage_object_acl`'s Read function makes the tests
pass.