[Pantsd] Investigate which of the calls to time.sleep() we can remove from test_pantsd_integration.py

[blorente]

It seems like many of the calls to time.sleep() are just waiting for the daemon to start up, which may be passed as a timeout to assert_started(), and that function will poll for the pid until it appears.

We may also need to add more sophisticated polling for things other than the pid appearing (such as "python has started running")

[stuhood]

Cleaned up a few of these recently in #9660.