[3.12] gh-110178: Use fewer weakrefs in test_typing.py (GH-110194) (#110224)

gh-110178: Use fewer weakrefs in test_typing.py (GH-110194)

Confirmed that without the C changes from GH-108517, this test still segfaults with only 10 weakrefs.
(cherry picked from commit 732ad44cec971be5255b1accbac6555d3615c2bf)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>