try_cast_literal_to_type doesn't respect timestamp precision #5507

#[test]
fn test_repro() {
    let new_scalar = try_cast_literal_to_type(
        &ScalarValue::TimestampNanosecond(Some(123456), None),
        &DataType::Timestamp(TimeUnit::Microsecond, None)
    ).unwrap().unwrap();

    // This passes which is wrong
    assert_eq!(new_scalar, ScalarValue::TimestampMicrosecond(Some(123456), None));

    // This fails!
    // assert_eq!(new_scalar, ScalarValue::TimestampMicrosecond(Some(123), None));
}

// This should be the correct result
assert_eq!(new_scalar, ScalarValue::TimestampMicrosecond(Some(123), None));