Add min_age_to_force_merge_on_partition_only setting for partition optimization

Why it matters

This feature allows users to efficiently optimize old data parts by forcing merges at the partition level, which can improve performance and resource utilization by avoiding unnecessary merges of more recent parts.

How to use it

Set the min_age_to_force_merge_on_partition_only setting in the configuration or query context to specify the minimum age of parts that should be merged only on the partition level. This enables targeted merging of old parts without affecting newer data.