[prop250] Fix a time parsing error on platforms with 32 bit time_t
On platforms with 32 bit time_t, tor can't parse some dates in 2038, and all dates after 2038. So using 2666 in test data doesn't work.
My branch sr-32bit on https://github.com/teor2345/tor.git fixes this issue, which is T9 from #16943 (moved).