TST: Tests for replace method when column contains pd.NA (#47480)
- [X] closes #47480
- [X] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [X] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Added tests to show BUG from issue (#47480).
Original issue was about pd.Series method (`df["A"].replace`), but pushing tests for both DataFrame and Series.

Test failing when DataFrame/Series has dtype `object` (infered when `dtype=None` on constructor).
Looks like the added tests are failing in the CI. Are you interested in contributing a fix? Last commit seems to pass all tests.
Should I make any other changes to the code? @phofl Now it only creates the NA mask if `arr` is a numpy.ndarray (happens when Series dtype is object. Otherwise arr is a pandas.array e.g. IntegerArray or FloatingArray. There is no ObjectArray class?).

Saw a problem after commiting:
```
    else:
        arr_nas = mask  # Avoid possibility of NameError on new_mask[~arr_nas]
```
Should change to `mask.copy()` or delete it altogether? This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this.