GH-107458: fix test_tools refleak

[kumaraditya303]

• Issue: test_tools are leaked #107458

[kumaraditya303]

I have verified this locally, I'll merge as the buildbots are all already broken, will check later when things are better.

[Eclips4]

Are this really solve the issue?
this code still leaks:

importsysimportimportlibname="_decimal"importlib.import_module(name)
sys.modules.pop(name)
./python.exe-Xshowrefcountexample.py
[7624refs, 4253blocks]

[kumaraditya303]

Nope, this fixes this test which was false leaking, you should try running the test_tools on current main branch.