[3.14] gh-142206: multiprocessing.resource_tracker: Decode messages using older protocol (GH-142215) (GH-142285)

(cherry picked from commit 4172644d78d58189e46424af0aea302b1d78e2de)

Difference from the original commit: the default in 3.14 is to use
the simpler original protocol (except for filenames with newlines).

Co-authored-by: Petr Viktorin <encukou@gmail.com>