gh-91916: Fix test_runpy on non-UTF-8 locale (GH-91920)

gh-91916: Fix test_runpy on non-UTF-8 locale (GH-91920)

If use a non-builtin codec, partially implemented in Python
(e.g. ISO-8859-15), a new RecursionError (with empty error message)
can be raised while handle a RecursionError.

Testing for error message was needed to distinguish
a recursion error from arbitrary RuntimeError. After introducing
RecursionError, it became unnecessary.
(cherry picked from commit a568585069174cec35ce26cdf4d4862c634d9f6d)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>