chore(api): use 0-sleeps to spin asyncio loops

In the cleanup of the thread manager, we were doing an
asyncio.sleep(0.1) to spin the loop to make sure some classes cleaned
up. Since then, we've learned that a 0-second sleep does the same thing.
Changing the 0.1 to 0 should not present any changes in behavior (and if
it does, they're in a cleanup method that is basically never run in
prod) and doubles the speed of the tests in hardware_control.

api/src/opentrons/hardware_control/thread_manager.py

@@ -268,10 +268,9 @@ def call_both() -> None:
  # so cancelled tasks can have a chance to complete.
  async def clean_and_notify() -> None:
  await wrapped_cleanup()
- # this sleep allows the wrapped loop to spin a couple
- # times to clean up the tasks we just cancelled. My kingdom
- # for an asyncio.spin_once()
- await asyncio.sleep(0.1)
+ # this sleep allows the wrapped loop to spin to clean up the
+ # tasks we just cancelled.
+ await asyncio.sleep(0)
 
  fut = asyncio.run_coroutine_threadsafe(clean_and_notify(), wrapped_loop)
  fut.result()