`prerelease_deps` session with `coroutine 'UnaryUnaryCall._invoke' was never awaited` with `pytest-asyncio>0.21.2`

See build log [here](https://btx.cloud.google.com/invocations/ab643240-d58f-4e60-812b-30521d3b5065/log) where the presubmit `Kokoro Prerelease Dependencies` which runs the `prerelease_deps` nox session fails with `RuntimeWarning: coroutine 'UnaryUnaryCall._invoke' was never awaited`

The issue only appears when using `pytest-asyncio>0.21.2`

```
tests/system/test_system_async.py::test_or_query_in_transaction[None] ERROR [ 49%]
tests/system/test_system.py::test_collections[system-tests-named-db] Exception ignored in:
Traceback (most recent call last):
File "/usr/local/google/home/partheniou/.pyenv/versions/3.12.0/lib/python3.12/warnings.py", line 552, in _warn_unawaited_coroutine
warn(msg, category=RuntimeWarning, stacklevel=2, source=coro)
RuntimeWarning: coroutine 'UnaryUnaryCall._invoke' was never awaited
FAILED
```