make dtype to be ignored in constructors if data is Series or DataFrame
The note in the docs added in #59300 wasn't sufficient: the dtype kwarg was ignored in certain cases. Set it to None if creating Series from another Series and the same for DataFrames. See GH pandas-dev#59060.

Request review from @mroeschke and @jorisvandenbossche

- [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.

No. Dtype keyword should not be silently ignored @jbrockmendel in the original PR I added a warning initially, though I was told that it's too noisy and a line in the docs [should be enough](https://github.com/pandas-dev/pandas/pull/59300#pullrequestreview-2194500140). Thus this PR just makes the code to act as said in the docs since the original PR is merged already. That PR was wrong. The keyword should never be silently ignored. [As I said in the issue](https://github.com/pandas-dev/pandas/issues/59060#issuecomment-2252256406) my PR should be reverted, I don't like the idea of silently ignoring the keywords. Though since the last one was approved I just decided to try to make it consistent. BTW ideas and suggestions are welcomed in the #59060. Thanks for the pull request, but it appears to have gone stale. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen.