TST: series offset artithmetic tests
…racting a series of DateOffsets to / from a series of Timestamps (test_series_add_daytime_offset, test_series_add_daytime_offset)

- [x] closes #19211
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry (omitted, test only)
