Major Description
When implementing date/timestamp functions, we notice inconsistent dtypes with PySpark, as shown below.
>> sdf.select(SF.current_timestamp()).toPandas().dtypes
current_timestamp() datetime64[ns]
dtype: object
>>> cdf.select(CF.current_timestamp()).toPandas().dtypes
current_timestamp() datetime64[ns, America/Los_Angeles]
Affected functions include:
to_timestamp, from_utc_timestamp, to_utc_timestamp, timestamp_seconds, current_timestamp, date_trunc
We may have to implement `is_timestamp_ntz_preferred` for Connect.
After the fix, tests of those date/timestamp functions which use `compare_by_show` should be switched to `toPandas` comparison.
