Revert "make test_transformed_gc tests more stable"

[olliemath]

Reverts #4868

This didn't seem to work - so something else must be at play here

[mattip]

Let's let this change run by the rpython nightly buildbot build, perhaps it will give us more data.

[mattip]

That specific test test_transformed_gc does not show up at all in the buildbot runs, neither before or after #4868. Some of the buildbots (macos-arm64 macos-x86_64, windows) use pypy2 as a test runner host python, and last night's run cleared up some other failures on macos-arm64 test.test_boehm, so maybe you are on to something? Are there other places that also need to call the GC to clear caches?

[mattip]

Here is the link to the rpython builbot runs, it also appears on the top navbar of the buildbot pages