DATE_TRUNC(<truncate field>, <date/datetime>) is a function that allows
the user to truncate a timestamp to the specified field by zeroing out
the rest of the fields. The function is implemented according to the
spec from PostgreSQL: https://www.postgresql.org/docs/current/functions-datetime.html#FUNCTIONS-DATETIME-TRUNCCloses: #46319
(cherry picked from commit b37e96712db1aace09f17b574eb02ff6b942a297)