Improved Backoff for Background Cleanup Tasks in MergeTree Settings

Why it matters

This feature enhances the efficiency and reliability of background cleanup operations in MergeTree tables by providing better control over the timing of cleanup tasks. Moving the relevant interval settings to merge tree settings centralizes control, reduces configuration complexity, and ensures that cleanup behavior is more consistent and manageable at the table engine level.

How to use it

To use the improved cleanup backoff, configure the new merge tree settings merge_tree_clear_old_temporary_directories_interval_seconds and merge_tree_clear_old_parts_interval_seconds in your MergeTree table settings as needed. These settings dictate the intervals for background cleanup of old temporary directories and parts. Since they have been moved from user settings, update your configurations accordingly to take effect.