…0857)

## Proposed changes

### Issue
```
/var/local/ldb-toolchain/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_vector.h:1046:9: runtime error: reference binding to null pointer of type 'doris::StringRef'
    #0 0x55ee63eb0418 in std::vector<doris::StringRef, std::allocator<doris::StringRef>>::operator[](unsigned long) /var/local/ldb-toolchain/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_vector.h:1046:2
    #1 0x55ee63eb0418 in doris::Status doris::vectorized::OrcReader::_decode_string_non_dict_encoded_column<false>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, COW<doris::vectorized::IColumn>::mutable_ptr<doris::vectorized::IColumn> const&, orc::TypeKind const&, orc::EncodedStringVectorBatch*, unsigned long) /home/zcp/repo_center/doris_master/doris/be/src/vec/exec/format/orc/vorc_reader.cpp:1172:39
    #2 0x55ee63ea2685 in doris::Status doris::vectorized::OrcReader::_decode_string_column<false>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, COW<doris::vectorized::IColumn>::mutable_ptr<doris::vectorized::IColumn> const&, orc::TypeKind const&, orc::ColumnVectorBatch*, unsigned long) /home/zcp/repo_center/doris_master/doris/be/src/vec/exec/format/orc/vorc_reader.cpp:1124:16
    apache#3 0x55ee63e97e7a in doris::Status doris::vectorized::OrcReader::_fill_doris_data_column<false>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, COW<doris::vectorized::IColumn>::mutable_ptr<doris::vectorized::IColumn>&, std::shared_ptr<doris::vectorized::IDataType const> const&, orc::Type const*, orc::ColumnVectorBatch*, unsigned long) /home/zcp/repo_center/doris_master/doris/be/src/vec/exec/format/orc/vorc_reader.cpp:1365:16
    apache#4 0x55ee63b0e450 in doris::Status doris::vectorized::OrcReader::_orc_column_to_doris_column<false>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, COW<doris::vectorized::IColumn>::immutable_ptr<doris::vectorized::IColumn>&, std::shared_ptr<doris::vectorized::IDataType const> const&, orc::Type const*, orc::ColumnVectorBatch*, unsigned long) /home/zcp/repo_center/doris_master/doris/be/src/vec/exec/format/orc/vorc_reader.cpp:1532:5
    apache#5 0x55ee63e99622 in doris::Status doris::vectorized::OrcReader::_fill_doris_data_column<false>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, COW<doris::vectorized::IColumn>::mutable_ptr<doris::vectorized::IColumn>&, std::shared_ptr<doris::vectorized::IDataType const> const&, orc::Type const*, orc::ColumnVectorBatch*, unsigned long) /home/zcp/repo_center/doris_master/doris/be/src/vec/exec/format/orc/vorc_reader.cpp:1410:9
    apache#6 0x55ee63b0e450 in doris::Status doris::vectorized::OrcReader::_orc_column_to_doris_column<false>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, COW<doris::vectorized::IColumn>::immutable_ptr<doris::vectorized::IColumn>&, std::shared_ptr<doris::vectorized::IDataType const> const&, orc::Type const*, orc::ColumnVectorBatch*, unsigned long) /home/zcp/repo_center/doris_master/doris/be/src/vec/exec/format/orc/vorc_reader.cpp:1532:5
    apache#7 0x55ee63ad4f86 in doris::vectorized::OrcReader::get_next_block_impl(doris::vectorized::Block*, unsigned long*, bool*) /home/zcp/repo_center/doris_master/doris/be/src/vec/exec/format/orc/vorc_reader.cpp:1714:13
    apache#8 0x55ee63ad093b in doris::vectorized::OrcReader::get_next_block(doris::vectorized::Block*, unsigned long*, bool*) /home/zcp/repo_center/doris_master/doris/be/src/vec/exec/format/orc/vorc_reader.cpp:1547:5
```
### Solution
[Fix] (orc-reader) Fix StringRef nullptr data in orc-reader. When string
is empty in orc row batch, the data can point anything, maybe nullptr,
StringRef has undefined behavior when data is nullptr.

Related with apache#37845.