DEPR: removing to_long and toLong, deprecated in 0.7.0
- [X] closes #19077 
- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] whatsnew entry

  
can you add a note to the Deprecations section. Also can you see if you can see when this was deprecated originally? its not in our master list. @jreback I created an issue, with the information on when it was deprecated (in 2011), and added the note in whatsnew doc. Thanks a lot for the reviews, they're really helpful. Please let me know if this requires something else. lgtm. ping on green. thanks!