Add additional test cases for a leap year

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/139171



Merged-by: Illya Klymov <xanf@xanf.me>
Approved-by: Deepika Guliani <dguliani@gitlab.com>
Co-authored-by: Ezekiel Kigbo <ekigbo@gitlab.com>