GH-90985: Revert "Deprecate passing a message into cancel()" (GH-97999)

Reason: we were too hasty in deprecating this.
We shouldn't deprecate it before we have a replacement.
(cherry picked from commit 09de8d7aafece264720afbca3052a63eee413b73)

Co-authored-by: Guido van Rossum <guido@python.org>