REGR: Performance of DataFrame.stack where columns are not a MultiIndex
- [x] closes #57302 (Replace xxxx with the GitHub issue number)
- [ ] [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
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] 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.

Thanks @DeaMariaLeon for identifying this regression and @jorisvandenbossche for the solution used here.

ASVs

```
| Change   | Before [e51039af] <enh_fillna_allow_none~1>   | After [664c54b8] <regr_perf_stack>   |   Ratio | Benchmark (Parameter)                                                  |
|----------|-----------------------------------------------|--------------------------------------|---------|------------------------------------------------------------------------|
| -        | 304±2ms                                       | 44.2±0.4ms                           |    0.15 | reshape.ReshapeExtensionDtype.time_stack('datetime64[ns, US/Pacific]') |
| -        | 304±2ms                                       | 43.7±0.2ms                           |    0.14 | reshape.ReshapeExtensionDtype.time_stack('Period[s]')                  |
| -        | 294±0.7ms                                     | 40.8±0.3ms                           |    0.14 | reshape.ReshapeMaskedArrayDtype.time_stack('Float64')                  |
| -        | 291±2ms                                       | 40.7±0.2ms                           |    0.14 | reshape.ReshapeMaskedArrayDtype.time_stack('Int64')                    |
```
Thanks @rhshadrach 