Function prepare_sst_meta 

pub(crate) async fn prepare_sst_meta(
    file_path: &str,
    parquet_metadata: ParquetMetaData,
    region_metadata: Option<RegionMetadataRef>,
    page_index_policy: PageIndexPolicy,
) -> Result<SstMetaPreparation>

Decodes SST metadata and attempts to encode both cache representations on the blocking runtime.