Bug: infinite loop in `CalendarDateUntil` calculation

[nekevss]

While migrating Boa to temporal_rs in boa-dev/boa#3694, an infinite loop was discovered in the calendar.prototype.dateUntil test suite.

Cause: most likely occurs here in the diff_iso_date function.

Test 262 tests: The loop occurs in the largest-unit-year.js tests.

[jedel1043]

Would be good to port the test from JS to native Rust