BUG: DTA/TDA/PA iadd/isub should actually be inplace
- [x] closes #24115
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

did we ever deprecate the i place ops for Index? > did we ever deprecate the i place ops for Index?

They dont produce any kind of warnings, but they dont actually operate inplace > > did we ever deprecate the i place ops for Index?
> 
> They dont produce any kind of warnings, but they dont actually operate inplace

right and since they are immutable objects we shouldn’t
allow it anyhow.  thanks