ASV: add GroupBy.sum benchmark with timedelta and integer types
- [x] closes #20660
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests).
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added new benchmark to `GroupBy.sum` method with `timedelta64` and `int64` types.

Thanks @josemayer 