Incorrect Not predicate evaluation in ORC filtering pushdown

[Flyangz]

Describe the bug
The Not predicate evaluation in row group filtering was incorrect.
datafusion-contrib/orc-rust#78

To Reproduce

test("test string type filter for orc table") {
  withTable("orc_string_filter") {
    sql("create table orc_string_filter(id int, b string) using orc")
    sql("insert into orc_string_filter values (1, 'abc'), (2, null), (3, 'def')")
    checkSparkAnswerAndOperator("select * from orc_string_filter where b is not null")
  }
}

Additional context
Perhaps we should temporarily disable ORC predicate pushdown.