test: correct the RG config fixture to a shape the server accepts

- RG configs take no `version` key, and a label's mask goes under
  `preset_mask` rather than being mapped to a bare string
- The client treats `config_yaml` as an opaque string, so no test caught
  this; the fixture's only reader is whoever copies it as an example

Author: carlosfunk

tests/test_rg_configs.py

@@ -18,7 +18,7 @@
 CONFIG_ID_1 = "aaaaaaaa-1111-2222-3333-444444444444"
 CONFIG_ID_2 = "bbbbbbbb-1111-2222-3333-444444444444"
 
-CONFIG_YAML = "version: '1.0'\nlabels:\n  full_name: person_full_name\n"
+CONFIG_YAML = "labels:\n  full_name:\n    preset_mask: first_name_mask\n"
 
 
 @pytest.fixture