Avoid per-row dictionary casts for binary Parquet columns #26976

When Parquet dictionary promotion is enabled and binary_as_string maps a physical LargeBinary column to Dictionary(Int32, Utf8), the reader currently emits LargeBinary and DecoderProjection dictionary-encodes every row. In ClickBench Q23, pack_byte_to_dictionary and GenericByteDictionaryBuilder::append_array dominate the remaining dictionary regression.

The Parquet reader can preserve the on-disk dictionary by reading Dictionary(Int32, LargeBinary) and letting the projection cast only the distinct dictionary values to Utf8. The same approach applies to Utf8/LargeUtf8 offset-width mismatches. This keeps key decoding native while preserving the table schema and existing cast validation.