remove unnecessary timestamp parquet conversion

[eshishki]

I have parquet files with timestamptz type. It is kinda slow as reported here #47841

I want to avoid paying that tax and create parquet table with native datetime column type.
Starrocks create parquet file with timestamp_ntz type.

Now not only do we continue to pay conversion tax, but it is 5 times slower.

[DorianZheng]

@eshishki Got it. Will optimize it ASAP