This only arises when the system locale tells us to use its zero as
our zero digit, since no CLDR locale uses it by default. Adapt an
MS-specific QLocale::system() test to use Suzhou numbering, so as to
test this.
While updating the locale-restoration code to also restore the digits
being set in that test, add restore code for the long time format,
where previously only the short time format was restored. Add a
comment to make it less likely one of those shall be missed in future.
Fixes: QTBUG-85409
Change-Id: I343324bb563ee0e455dfe77d4825bf8c3082ca30
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>