close_loop coroutine instantiated but never awaited in (old?) asyncio loop integration

I was trawling through the source code and I spotted what looks to me like a possible bug here:
https://github.com/ipython/ipykernel/blob/d4a8703593cbe5d82bc955d68543dc623f5b4510/ipykernel/eventloops.py#L455

This instantiates a coroutine that never gets awaited. Calling an async def function just returns a coroutine object and does not start evaluating the function until the coroutine is started.

Additional poking around makes it look like asyncio loop integration here is actually semi-dead code from an era when the tornado event loop and asynio event loop where not the same event loop (tornado < 5?). Seems like this should be cleaned up, as my read is this old asyncio loop integration is not being maintained. Maybe a deprecation warning should be displayed if anyone tries to use `%gui asyncio` or something?

Start with ipykernel/eventloops.py around line 455 and inspect the `%gui asyncio` integration, including how close_loop is called. Check whether this path is still supported and whether the unawaited-coroutine issue can be reproduced. Done means the supported behavior is explicit and the issue is resolved or the obsolete path is cleanly deprecated.

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