DOC: add note to docstring about `dtype` keyword when creating Series from abother Series
When creating Series from another Series `dtype` keyword is not not used. Add note on `dtype` keyword to Series and DataFrame constructor. See GH #59060.

- [x] closes #59060 
- [ ] [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 [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.

Undo the previous changes and add a note to the `dtype` keyword on `pd.Series` and `pd.DataFrame` that says that the keyword is ignored if `data` is Series and DataFrame correspondingly. Thanks @taranarmo  I was going to comment that I find this a bit surprising behaviour, and so whether we shouldn't rather consider this as a bug instead of documenting it. 

But from a quick check, it seems that the `dtype` argument in fact is _not_ ignored, at least not in all cases (https://github.com/pandas-dev/pandas/issues/59060 clearly shows there are also cases where it is indeed ignored):

```
In [18]: pd.Series(pd.Series([1.0], dtype=float), dtype=int)
Out[18]: 
0    1
dtype: int64
```

Here it does cast the float series to an int64 dtype, so the `dtype` keyword was not ignored.

Will also comment on the issue, but so it seems the simple "If ``data`` is Series then is ignored." message added in this PR is not fully correct. IIUC I agree with Joris. The solution is not to change the doc, but to make the behavior consistent. The dtype kwarg should never be silently ignored.