Fix reference cycle in our test suite (#106328)
In certain cases we capture ErrorMeta in a list. The ErrorMeta objects hold
tracebacks which contain a frame with a local variable that refers to that list.
This change mutates the list on exit from the frame so that it doesn't refer
to the ErrorMeta objects, breaking the cycle.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106328
Approved by: https://github.com/huydhn
