test: use Windows asyncio policy in "non-asyncio" pool tests

test: use Windows asyncio policy in "non-asyncio" pool tests

In commit b6cc8343159fc0a27365e09a3beef06433f3f1b5, we drop the global
asyncio.set_event_loop_policy() for Windows in conftest.py, replacing it
with asyncio_options to be used by the anyio test runner. However, test
cases in test_pool_async_noasyncio.py are not "async def" so they would
not use that anyio runner (nor did they use pytest-asyncio's runner
before); but they need the event loop policy for Windows still.
Accordingly, we configure the loop from "anyio_backend_options" in
asyncio_run() fixture.