chore: Fix flaky test_actor_handles_migrating_event_correctly (#704)

### Description:
Do run run persist state event every 500 ms to prevent flakiness. It is
enough to check the persist state event we send manually and the Crawler
final one.

### Issues:

Closes: #703

Author: Pijukatel

tests/unit/actor/test_actor_lifecycle.py

@@ -220,7 +220,6 @@ async def test_actor_handles_migrating_event_correctly(monkeypatch: pytest.Monke
     """Test that Actor handles MIGRATING events correctly by emitting PERSIST_STATE."""
     # This should test whether when you get a MIGRATING event,
     # the Actor automatically emits the PERSIST_STATE event with data `{'isMigrating': True}`
-    monkeypatch.setenv(ApifyEnvVars.PERSIST_STATE_INTERVAL_MILLIS, '500')
     monkeypatch.setenv(ApifyEnvVars.IS_AT_HOME, '1')
     monkeypatch.setenv(ActorEnvVars.RUN_ID, 'asdf')
 
@@ -285,9 +284,8 @@ async def handler(websocket: websockets.asyncio.server.ServerConnection) -> None
 
                 await asyncio.sleep(1)
 
-    assert len(persist_state_events_data) >= 3
-
-    print(persist_state_events_data)
+    # It is enough to check the persist state event we send manually and the crawler final one.
+    assert len(persist_state_events_data) >= 2
 
     # Expect last event to be is_migrating=False (persistence event on exiting EventManager)
     assert persist_state_events_data.pop() == EventPersistStateData(is_migrating=False)