SEP-1735: Switch unused worker_loop_env requests to usefixtures in test_celery_settings_override.py (#1451)

Four tests in `TestWorkerRefresherHandlers` requested the
`worker_loop_env` fixture purely for its setup side effects (dedicated
event loop, in-memory Tasks DB) without ever reading its returned
`(loop, session_maker)` tuple, leaving the module inconsistent with the
sibling suite's `usefixtures` convention for the same intent.

### Changes
- Switched `test_shutdown_cancels_and_drains_started_refresher` and
`test_init_is_idempotent_when_already_running` from a `worker_loop_env`
parameter with a discarded `loop, _ = worker_loop_env` unpack to
`@pytest.mark.usefixtures("worker_loop_env")`
- Switched `test_init_forwards_a_budget_from_worker_proc_alive_timeout`
and `test_init_returns_with_a_running_refresher_when_the_seed_hangs`
from an unused `worker_loop_env: WorkerLoopEnv` parameter to
`@pytest.mark.usefixtures("worker_loop_env")`
- Left `test_post_init_override_visible_after_loop_driven` and
`test_overridden_ttl_excludes_recently_locked_row` unchanged, since both
actually read `loop`/`maker` from the unpacked tuple

```python
@pytest.mark.usefixtures("worker_loop_env")
def test_shutdown_cancels_and_drains_started_refresher(self):
    """Stop and drain the started refresher, clearing the handle."""
    start_settings_override_refresher()
    ...
```

No test assertions or fixture setup/teardown behavior changed — this is
a call-site style change only.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: yyyyyyyan <24644216+yyyyyyyan@users.noreply.github.com>
Co-authored-by: yyyyyyy <yan.orestes@percona.com>

Author: Copilot

tests/app/tasks/test_celery_settings_override.py

@@ -63,7 +63,6 @@
 from tests.app.factories import TaskFactory
 
 ANCHOR = datetime(2026, 1, 1, 12, 0, 0, tzinfo=UTC)
-WorkerLoopEnv = tuple[asyncio.AbstractEventLoop, async_sessionmaker]
 
 
 def _write_cert(path: Path, *, not_valid_after: datetime) -> None:
@@ -300,9 +299,9 @@ def test_shutdown_is_noop_when_not_started(self, monkeypatch):
         stop_settings_override_refresher()
         assert celery_module._refresher.task is None
 
-    def test_shutdown_cancels_and_drains_started_refresher(self, worker_loop_env):
+    @pytest.mark.usefixtures("worker_loop_env")
+    def test_shutdown_cancels_and_drains_started_refresher(self):
         """Stop and drain the started refresher, clearing the handle."""
-        loop, _ = worker_loop_env
         start_settings_override_refresher()
         task = celery_module._refresher.task
         assert task is not None
@@ -312,9 +311,9 @@ def test_shutdown_cancels_and_drains_started_refresher(self, worker_loop_env):
         assert celery_module._refresher.task is None
         assert task.cancelled() or task.done()
 
-    def test_init_is_idempotent_when_already_running(self, worker_loop_env):
+    @pytest.mark.usefixtures("worker_loop_env")
+    def test_init_is_idempotent_when_already_running(self):
         """Keep the running refresher and start no second task on re-entry."""
-        loop, _ = worker_loop_env
         start_settings_override_refresher()
         first_task = celery_module._refresher.task
         assert first_task is not None
@@ -340,9 +339,9 @@ def test_post_init_override_visible_after_loop_driven(self, worker_loop_env):
         loop.run_until_complete(refresh_all(lambda: maker, _tasks_proxies()))
         assert baseline + 1234 == tasks_settings.STALENESS_THRESHOLD_SECONDS
 
+    @pytest.mark.usefixtures("worker_loop_env")
     def test_init_forwards_a_budget_from_worker_proc_alive_timeout(
         self,
-        worker_loop_env: WorkerLoopEnv,
         monkeypatch: pytest.MonkeyPatch,
     ) -> None:
         """Derive the seed budget from Celery's prefork liveness deadline."""
@@ -354,9 +353,9 @@ def test_init_forwards_a_budget_from_worker_proc_alive_timeout(
 
         assert recorded["seed_timeout"] == pytest.approx(6.0 * SEED_TIMEOUT_FRACTION)
 
+    @pytest.mark.usefixtures("worker_loop_env")
     def test_init_returns_with_a_running_refresher_when_the_seed_hangs(
         self,
-        worker_loop_env: WorkerLoopEnv,
         monkeypatch: pytest.MonkeyPatch,
     ) -> None:
         """Keep the periodic refresher after a hanging seed hits its budget."""