TST: Added a test for groupby.prod
- [x] Closes #46573 

- The bug related to issue #46573  has been fixed in the current version.

- Added a test related to this issue. The test is designed to check if `groupby.prod` returns the same results as `prod`.

Hi @rhshadrach , thank you for your review and suggestions. I have updated the code based on your feedback. Please review. Appreciate your help and guidance! Thanks @ccccjone!