[3.13] gh-128588: gh-128550: remove eager tasks optimization that missed and introduced incorrect cancellations (GH-129063) (#129089)

gh-128588: gh-128550: remove eager tasks optimization that missed and introduced incorrect cancellations (GH-129063)
(cherry picked from commit ed6934e71e55d398df8263f4697f58e4a3815f69)

Co-authored-by: Thomas Grainger <tagrain@gmail.com>
Co-authored-by: Kumar Aditya <kumaraditya@python.org>