test: remove scheduler race from snapshot freshness check

tests/test_live_snapshot.py

@@ -325,11 +325,13 @@ async def test_live_snapshot_keeps_fresh_activity_when_work_fails(monkeypatch):
 @pytest.mark.anyio
 async def test_live_snapshot_reuses_completed_snapshot_inside_freshness_window(monkeypatch):
     user_calls = 0
+    user_started = asyncio.Event()
     release = asyncio.Event()
 
     async def user():
         nonlocal user_calls
         user_calls += 1
+        user_started.set()
         return {"id": 1, "login": "timmy"}
 
     async def blocked_repos():
@@ -350,13 +352,8 @@ async def test_live_snapshot_reuses_completed_snapshot_inside_freshness_window(m
     monkeypatch.setattr(main, "notifications", empty)
 
     first = asyncio.create_task(main.live_snapshot())
-    await asyncio.sleep(0)
+    await user_started.wait()
     second = asyncio.create_task(main.live_snapshot())
-    for _ in range(100):
-        if user_calls:
-            break
-        await asyncio.to_thread(lambda: None)
-    assert user_calls == 1
 
     release.set()
     await asyncio.gather(first, second)