gh-97527: IDLE - fix buggy macosx patch (GH-98313)

GH-97530 fixed IDLE tests possibly crashing on a Mac without a GUI.
But it resulted in IDLE not starting in 3.10.8, 3.12.0a1, and
Microsoft Python 3.10.2288.0 when test/* is not installed.
After this patch, test.* is only imported when testing on Mac.
(cherry picked from commit 35fa5d5e7f2b0971b39b2659dc70cb77e34a7dd6)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>