[libc++] Fix localization failures on macOS 15.4 (#138744)

This patch reverts e15025dd and 88e15b781 which were temporary measures
until we had figured out the underlying issues. It turns out that recent
OSes updated localization data, removing the need for several Apple-specific
workarounds in the tests.

Fixes #135385

NOKEYCHECK=True
GitOrigin-RevId: a98295dbcf500a21ea10e2124b6521a3124da643
1 file changed