test: use Europe/Helsinki instead of Europe/Kyiv in test-calendarspec

test: use Europe/Helsinki instead of Europe/Kyiv in test-calendarspec

Europe/Kyiv was added somewhat recently. Use Europe/Helsinki which is
much older and thus works with older tzdata like version 2022a.

line 193: "2016-03-27 03:17:00" new_tz=:Europe/Kyiv
At: Sun 2016-03-27 03:17:00.000000 Europe
Assertion 'r == -ENOENT' failed at src/test/test-calendarspec.c:70, function _test_next(). Aborting.

Follow-up for aa077884c13769ae3bd6aa98978b4ac9e64b5365

(cherry picked from commit f391d6c9ba1277a2d148f30db18fc615763a834d)