TST: GH30999 add match=msg to 2 pytest.raises in pandas/tests/io/json/test_normalize.py
xref #30999 for pandas/tests/io/json/test_normalize.py

And with this my work on #30999 is done. Will head over to the issue to explain why I am not fixing the remaining 15 instances of `pytest.raise`

- [ ] closes #xxxx
- [ ] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry
