fix unnecessary sort in pd.read_json and orient="index"
- [x] closes #28557 
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Looks simpler - nice job! Can you also add a whatsnew for v1.0.0? Of course. Looks like an isort failure is causing CI to go red, but outside of that this change lgtm Looks like you still have an isort error. Can you run `isort pandas/io/json/_json.py` locally and push up the result? Thanks @KimDoubleB - great PR and congrats on first contribution! Thanks so much. @WillAyd 
I’m really grateful for your help.