`test_get_yaml_plugin` fails in isolation when registry JSON is missing or stale

Requested Update

Description

• test_get_yaml_plugin and the newly-introduced ( #17 ) test_get_yaml_plugin_raises_plugin_validation_error_on_bad_yaml fail with KeyError: 'configs' when run in isolation, because PluginRegistryValidator does not reliably populate registered_plugins["yaml_based"] if the on-disk registry JSON is missing or empty at module-import time.

Background and Motivation

• The validator is instantiated as a class attribute on TestPluginRegistry at import time. Its registry_files list is computed during that instantiation.
• If the on-disk registered_plugins.json is missing or contains an empty yaml_based section at that moment, later calls to _set_class_properties(force_reset=True, rebuild_registries_override=True) do not always recover -- the in-memory dict ends up with yaml_based: {}.
• Running tests in their default order works because earlier tests warm up the registry. Running an individual test in isolation (or with pytest's --last-failed ordering) breaks. This was discovered while working on PR #17.

Code to demonstrate issue

• From a clean state, delete the on-disk registry JSON and run a single test:

rm /home/<user>/.cache/geoips/pluginify.plugin_packages/pluginify/registered_plugins.json
pytest tests/unit_tests/plugin_registries/test_plugin_registries.py::TestPluginRegistry::test_get_yaml_plugin -v

Expected: test passes after auto-rebuild. Actual: KeyError: 'configs'.

Checklist for Completion

• Decide whether each test in TestPluginRegistry should be self-contained (set up its own registry state) or whether shared setup via a fixture is acceptable.
• Make test_get_yaml_plugin and similar tests pass when run in isolation.
• Confirm fix does not require contributors to manually run pluginify create before running the test suite.