build: remove experimental Python 3 tests

These tests do not help us to get closer to Python 3 compatibility and
they take up valuable time yet they always fail.

PR-URL: https://github.com/nodejs/node/pull/29413


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>