Concat with axis rows
- [x] closes #14369 
- [x] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [x] whatsnew entry

I closed #14389 and opened with one in hopes of the new commits showing up.

Edit: Didn't realize you already knew this/it was just weirdness with the repo
 Thanks for the tip @paul-mannino !  I'll do that next time.
 ## [Current coverage](https://codecov.io/gh/pandas-dev/pandas/pull/14416?src=pr) is 85.26% (diff: 100%)

> Merging [#14416](https://codecov.io/gh/pandas-dev/pandas/pull/14416?src=pr) into [master](https://codecov.io/gh/pandas-dev/pandas/branch/master?src=pr) will increase coverage by **<.01%**

``` diff
@@             master     #14416   diff @@
==========================================
  Files           140        140          
  Lines         50634      50642     +8   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits          43173      43181     +8   
  Misses         7461       7461          
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [7d40f18...9aa260d](https://codecov.io/gh/pandas-dev/pandas/compare/7d40f18718ba80e8b8d706eaed2fc4c098686e71...9aa260d5ca21eb3acbd790fbb8812bfa94e60c8d?src=pr)
 Actually, just using the `DataFrame` `_get_axis_number` causes tests with `Panel`s to fail.  I've updated it to use the `DataFrame` method if a `Series` is passed and to use the object itself (`sample`) otherwise.
 Looks good to me
 thanks!
