Improve way parquet metadata size is handled

[rdettai]

The parquet metadata size is not known from the catalog. Having a dedicated call to the footer containing the metadata size would also be quite inefficient. This is why currently the first call downloads 1MB at the end of the file and hopes that the entire metadata will be within this range:

• on one side 1MB is kind of large and download duration is not negligible
• at the same time, parquet metadata can be large for files with many row groups

Solutions might be:

• reduce the default size to 256KB and implement the logic that fetches the rest of the metadata if it didn't fit in the initial dl