[3.13] gh-125245: Fix race condition when importing `collections.abc` (GH-125415) (GH-125944)

If multiple threads concurrently imported `collections.abc`, some of the
threads might incorrectly see the "shim" `Lib/collections/abc.py` module
instead of the correct `Lib/_collections_abc.py` module.  This affected
both the free threading build and the default GIL-enabled build.
(cherry picked from commit fed501d7247053ce46a2ba512bf0e4bb4f483be6)

Co-authored-by: Sam Gross <colesbury@gmail.com>