bpo-32726: Do not force IDLE.app to launch in 32-bit mode. (GH-6280)

bpo-32726: Do not force IDLE.app to launch in 32-bit mode. (GH-6280)

Forcing the macOS IDLE.app gui process to launch in 32-mode was
a necessary hack for old versions of Tk (Aqua Carbon as in Tk 8.4
and early versions of 8.5); it is not needed for current versions
of Tk.  Since 32-bit launching will no longer be supported on
future releases of macOS, allow IDLE.app to launch in 64-bit mode.
(cherry picked from commit df532ab752680f6e359672c2cd40bec8ac848628)

Co-authored-by: Ned Deily <nad@python.org>