test-time-util: restore relaxation of check is special timezones

test-time-util: restore relaxation of check is special timezones

Fixup for 514fa9d39ae9935ef1e014a3dd48dd5856007df2. We are now getting
failures in CI i386 builds in Fedora rawhide:
  TZ=Europe/Lisbon, tzname[0]=WET, tzname[1]=WEST
  @212545617716594 → Sun 1976-09-26 00:26:57 WET → @212542017000000 → Sun 1976-09-26 00:26:57 CET
  src/test/test-time-util.c:450: Assertion failed: Expected "ignore" to be true

Restore the conditionalization for CAT, EAT, WET that was removed
in the refactoring.