Remove explicit loop from asyncio tests

[QuLogic]

In Python 3.5.3 and 3.6, the get_event_loop returned the expected result always, so in Python 3.8, this parameter was deprecated and in 3.10 it was removed.

• Closes The loop parameter to Queue is deprecated/removed #5350
• Tests added / passed
• Passes pre-commit run --all-files

[QuLogic]

The failures do seem to be related, but I do not understand them as I tested with 3.9 and 3.10 and this seemed to have worked.

[QuLogic]

Hmm, no, actually, locally it didn't fail, but a scratch build in koji did. So it seems flaky to do this exactly. I guess the queue must be created when the right loop is running, and not pre-created.

[QuLogic]

The explicit loop in asyncio code was removed by #5709, so I've changed this to just remove the loop from the tests.

[github-actions]

Unit Test Results

       12 files  ±0         12 suites  ±0   6h 55m 39s ⏱️ - 17m 34s
  2 621 tests ±0    2 539 ✔️  - 1    80 💤 ±0  2 ❌ +2 
15 650 runs  ±0  14 790 ✔️ +4  858 💤  - 4  2 ❌ +1 

For more details on these failures, see this check.

Results for commit f7d28d4. ± Comparison against base commit b3f50ce.

[QuLogic]

The failing test appears unrelated.

[graingert]

the "_loop" attribute is there in 3.10 - it's just late bound: https://github.com/python/cpython/blob/8acbb93c0763fa53b5959fe05d86ba275c9e8a5b/Lib/asyncio/mixins.py#L28

the tests could be modified to use the asyncio resource first so the loop is always bound before the assert, eg:

await c.gather([c.submit(...)])
assert c._gather_semaphore._loop

[QuLogic]

Replaced by #5952.