Removing `@register_integration("asyncio")` and `def loop_asyncio(kernel):`

Inizia da ipykernel/eventloops.py intorno al codice di integrazione collegato e traccia come viene invocato da enter_eventloop() in kernelbase.py. Confronta il comportamento con le modifiche al ciclo di eventi asyncio descritte nella pull request 1469, quindi verifica che l’esecuzione ripetuta di %gui asyncio non faccia più aumentare il numero di task asyncio né sprechi CPU.

In current versions of ipykernel, when you execute in jupyter, vscode jupyter,

%gui asyncio

then after a while, when you execute

import asyncio
asyncio.all_tasks()```

you will get and see like

{<Task pending name='Task-52016' coro=<_async_in_context.<locals>.run_in_context() running at D:\test\ipykernel\ipykernel\utils.py:60> wait_for=<Task pending name='Task-52017' coro=<Kernel.shell_main() running at D:\test\ipykernel\ipykernel\kernelbase.py:621> cb=[Task.task_wakeup()]> cb=[ZMQStream._run_callback.<locals>._log_error() at e:\.pixi\envs\default\Lib\site-packages\zmq\eventloop\zmqstream.py:563]>, 
<Task pending name='Task-5217' coro=<Kernel.shell_main() running at D:\test\ipykernel\ipykernel\kernelbase.py:621> cb=[Task.task_wakeup()]>}

It keeps increasing task count and it wastes your some cpu resource in the background. It's acually running these below codes, it just enters the function the return repeatedly, by self.io_loop.call_later(0.001, advance_eventloop) of enter_eventloop() in kernelbase.py.
https://github.com/ipython/ipykernel/blob/8816d024bf730e9fdb051b44ab2fc1ee2276cea2/ipykernel/eventloops.py#L430-L473

How it happened:
The @register_integration("asyncio") and def loop_asyncio(kernel): was at the old ages, to drive the asyncio codes that inputed by users, like asyncio.ensure_future(...), when ipykernel was running under IOloop of tornado<6.1 which using the selectorloop or even older type eventloop. It was to make users able to run asyncio codes when the underhood is other things.
The current ipykernel its main loop is already asyncio loop, by IOloop of tornado>6.1. The user inputed asyncio codes already run in the main loop.

Therefore the related codes @register_integration("asyncio") and def loop_asyncio(kernel): could be deleted.

Solution:
related issue: https://github.com/ipython/ipykernel/pull/1469 solving the proactor and selector eventloop within asyncio