v.21.1Improvements

Fix Assert in HDFS Table Function and Add Test

Fix possible assert in hdfs table function/engine, add test. #31036 (Kruglov Pavel).
Fix a possible assertion failure in the hdfs table function and table engine, and add corresponding tests.

Why it matters

This update addresses a potential stability issue where an assertion could fail when using the hdfs table function/engine, improving the robustness and reliability of ClickHouse when interacting with HDFS storage.

How to use it

Users do not need to change their existing usage; the fix is applied internally to the hdfs table function and engine. Simply updating to the new ClickHouse version will ensure the issue is resolved.