Revert "fix: cleanup pending route handlers on close (#1412)"

[rwoll]

This reverts commit c8d8f4a.

• It's not exhaustive, and running the originally reported sample on 1.22 also yields errors.
• There are many other places where we do asyncio.create_task without awaiting from before async handlers where added, and they need to be dealt with too.
• We likely want to either loop over all tasks in the loop (assuming we created the loop) and kill them when we exit PW ContextManager, (2) more exhaustively track the background tasks (i.e. do what we do in this patch, but wrap some more create_async callsites), or (3) something else!

Relates 1402.