Casting Timestamp to date is off by one day for dates before 1970-01-01

[parthchandra]

If casting a negative number of micros/millis to date, the cast method divides by the number of (micro/milli)seconds to get the number of days from the beginning of the epoch.
For a timestamp like 1969/12/31 23:59:59.995 (in millis) the number of millis from beginning of the epoch is -5. The division by the number of seconds in a day yields 0 which is off by one day since it should be -1.

To Reproduce

select '1969-12-31 00:00:01'::timestamp::date;
+-----------------------------+
| Utf8("1969-12-31 00:00:01") |
+-----------------------------+
| 1970-01-01                  |
+-----------------------------+

Expected behavior

select '1969-12-31 00:00:01'::timestamp::date;
+-----------------------------+
| Utf8("1969-12-31 00:00:01") |
+-----------------------------+
| 1960-12-31                  |
+-----------------------------+

[comphead]

Reverified that on PG it works as @parthchandra expects

select '1969-12-31 00:00:01'::timestamp::date;


    date    
------------
 1969-12-31
(1 row)

[tustvold]

label_issue.py automatically added labels {'arrow'} from #4323