Fix Directory Already Exists Error in Temp Fetch Process

Why it matters

This fix addresses an issue where a failed attempt to fetch a data part could leave behind a temporary directory, causing subsequent fetch attempts to fail with the directory already existing. By deleting the temporary fetch directory if it exists, it improves the robustness and reliability of data fetching operations in ClickHouse.

How to use it

This fix is applied internally within ClickHouse and requires no user intervention. Simply upgrading to the version including this fix will prevent the tmp_fetch_XXX already exists error during part fetch failures.