test: fix remaining tests broken by task system redesign

Update all tests that created PaperlessTask objects with old field names
to use PaperlessTaskFactory and new field names (task_type, trigger_source,
status, result_message). Use apply_async instead of delay where mocked.
Drop TestCheckSanityTaskRecording — tests PaperlessTask creation that was
intentionally removed from check_sanity().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/documents/tests/test_api_app_config.py

@@ -831,7 +831,7 @@ class TestApiAppConfig(DirectoriesMixin, APITestCase):
         config.save()
 
         with (
-            patch("documents.tasks.llmindex_index.delay") as mock_update,
+            patch("documents.tasks.llmindex_index.apply_async") as mock_update,
             patch("paperless_ai.indexing.vector_store_file_exists") as mock_exists,
         ):
             mock_exists.return_value = False