PERF: future_stack=True with non-MulitIndex columns
- [x] closes #58391 (Replace xxxx with the GitHub issue number)
- [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).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.


```python
df = pd.DataFrame(np.random.random(size=(10000, 100)))
%timeit df.unstack()
17.2 ms ± 159 μs per loop (mean ± std. dev. of 7 runs, 100 loops each)  <--- PR
205 ms ± 3.37 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)     <--- main
```
@jbrockmendel - the failing tests are:

```
FAILED pandas/tests/extension/test_numpy.py::TestNumpyExtensionArray::test_stack[float-True-columns0] - AssertionError: (<class 'numpy.dtypes.Float64DType'>, dtype('float64')) vs (<class 'pandas.core.dtypes.dtypes.NumpyEADtype'>, NumpyEADtype('float64'))
FAILED pandas/tests/extension/test_numpy.py::TestNumpyExtensionArray::test_stack[object-True-columns0] - AssertionError: (<class 'numpy.dtypes.ObjectDType'>, dtype('O')) vs (<class 'pandas.core.dtypes.dtypes.NumpyEADtype'>, NumpyEADtype('object'))
```

This happens because of some monkey-patching

https://github.com/pandas-dev/pandas/blame/3b48b17e52f3f3837b9ba8551c932f44633b5ff8/pandas/tests/extension/test_numpy.py#L72-L73

It's not clear to me if the code should handle this case, or if this behavior is okay and the test should be modified. Was wondering if you had any experience dealing with this. The behavior is fine, the test should be patched 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. Thanks @rhshadrach 