test(worker): send the real startup signals, and import celery_init one way

The lifecycle tests imported docsgpt.celery_init as a module next to the
file's from-imports, which code scanning flags. Patch the flag by path and send
the signals from celery.signals -- the objects a worker actually fires.

tests/test_celery.py

@@ -322,20 +322,20 @@ class TestInWorker:
         # to one greenlet, so only the worker's own startup can say this
         # process is a worker. The lifecycle signal records that for every
         # thread and greenlet in it.
-        import docsgpt.celery_init as celery_init
+        from celery.signals import worker_init
 
-        monkeypatch.setattr(celery_init, "_IS_WORKER_PROCESS", False)
+        monkeypatch.setattr("docsgpt.celery_init._IS_WORKER_PROCESS", False)
         assert self._ask_from_a_new_thread() is False
 
-        celery_init.worker_init.send(sender=None)
+        worker_init.send(sender=None)
 
         assert self._ask_from_a_new_thread() is True
 
     def test_prefork_children_record_it_on_their_own_start(self, monkeypatch):
-        import docsgpt.celery_init as celery_init
+        from celery.signals import worker_process_init
 
-        monkeypatch.setattr(celery_init, "_IS_WORKER_PROCESS", False)
-        celery_init.worker_process_init.send(sender=None)
+        monkeypatch.setattr("docsgpt.celery_init._IS_WORKER_PROCESS", False)
+        worker_process_init.send(sender=None)
 
         assert self._ask_from_a_new_thread() is True