TST (string dtype): resolve all xfails in JSON IO tests
While looking at centralizing `to_pandas()` conversion, I noticed that for JSON we are not yet handling the case of the string dtype for the pyarrow engine (engine, not dtype_backend), so it's a bit surprising actually that all tests are passing here ... Interesting - I didn't even realize we had a pyarrow engine for JSON!

Is your expectation that those cases would be returning `dtype=object` and cause a failure? > Is your expectation that those cases would be returning `dtype=object` and cause a failure?

Yes, at least if we have proper testing of it .. But let's do that in a next PR, going to merge this one already Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

```
git checkout 2.3.x
git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
git cherry-pick -x -m1 9bc88c79e6fd146a44970309bacc90490fdec590
```

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

```
git commit -am 'Backport PR #60318: TST (string dtype): resolve all xfails in JSON IO tests'
```

4. Push to a named branch:

```
git push YOURFORK 2.3.x:auto-backport-of-pr-60318-on-2.3.x
```

5. Create a PR against branch 2.3.x, I would have named this PR:

> "Backport PR #60318 on branch 2.3.x (TST (string dtype): resolve all xfails in JSON IO tests)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the `Still Needs Manual Backport` label once the PR gets merged.

If these instructions are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                 Alright - I'll take a look. I wonder if there's some post-processing in JSON that is masking that...

I'll take care of the backport as well. Thanks for merging Manual backport -> https://github.com/pandas-dev/pandas/pull/60327