Description Controls how to download segments from bucket storage when prefetching

Sets how LogScale chooses segments to download from bucket storage when prefetching. If S3_STORAGE_PREFERRED_COPY_SOURCE is false, the prefetcher will only download segments that are not already on another host. Otherwise, it will download as many hosts as necessary to follow the configured replication factor. This should help avoid excessive bucket downloads when nodes in the cluster have lots of empty disk space.