Don't import collection ABCs unless we know we need to.
Review Request #11943 — Created Jan. 20, 2022 and submitted — Latest diff uploaded
I had made the backport for collection ABCs work conditionally on
whether we could import correctly, but that ends up raising a warning.
This change updates it so we base it on Python version instead.
It's likely this can actually go away entirely, but that will come later
once we've settled all the dependencies.
Ran unit tests.