[BUGFIX] Fix DraftDatasourceConfigAction connection string substituti…

…on (#8613)

Co-authored-by: Josh Stauffer <josh@greatexpectations.io>

great_expectations/agent/actions/draft_datasource_config_action.py

@@ -25,6 +25,7 @@ def run(self, event: DraftDatasourceConfigEvent, id: str) -> ActionResult:
                 "DraftDatasourceConfigAction received an unknown datasource type."
             ) from exc
         datasource = datasource_cls(**draft_config)
+        datasource._data_context = self._context
         datasource.test_connection(
             test_assets=True
         )  # raises `TestConnectionError` on failure