gh-117482: Simplify the Fix For Builtin Types Slot Wrappers

[ericsnowcurrently]

In gh-121602, I applied a fix to a builtin types initialization bug.
That fix made sense in the context of some broader future changes,
but introduced a little bit of extra complexity. That fix has turned
out to be incomplete for some of the builtin types we haven't
been testing. I found that out while improving the tests.

A while back, @markshannon suggested a simpler fix that doesn't
have that problem, which I've already applied to 3.12 and 3.13.
I'm switching to that here. Given the potential long-term
benefits of the more complex (but still incomplete) approach,
I'll circle back to it in the future, particularly after I've improved
the tests so no corner cases slip through the cracks.

(This is effectively a "forward-port" of 716c677 from 3.13.)

• Issue: Weird int.__str__ behaviour inside sub-interpreters #117482