These were added back in commit c4935f3049
because the tests required CPython 3.8, which was quite new at the time.
But CPython 3.8 was released over 4 years ago (October 2019) and the CI
test runners, and developers, have this (or a more recent) CPython version.
Removing the .exp files also helps keep MicroPython semantics the same as
CPython.
The asyncio_fair.py test it adjusted slightly to have more deterministic
timing and output.
Signed-off-by: Damien George <damien@micropython.org>
