Re-enable SQL test

As of now SQL test for the extension is skipped because certain data is deleted from external website: https://github.com/duckdb/duckdb-httpfs/blob/85ac4667bcb0d868199e156f8dd918b0278db7b9/test/sql/copy/csv/test_csv_httpfs.test#L11-L12

When I was working on cached httpfs (which adds caching and parallel read wrapper around httpfs), I checked the CSV file into repository so it's hermetic.
Reference: https://github.com/dentiny/duck-read-cache-fs/tree/main/test/data

Start with test/sql/copy/csv/test_csv_httpfs.test at the skipped lines referenced in the issue, then inspect the test/data approach in the linked duck-read-cache-fs repository. Add the required CSV fixture to this repository and re-enable the SQL test; done means the test runs hermetically without relying on deleted external data.

Written by the indexing model from the issue text.