Do not delete files from s3 if they were not found locally

[sha-zo]

Now if some files are missing from the folder, they will be deleted from s3 when run clickhouse-backup upload.

I suppose the possibility, when the freeze only for the last few days partitions (partition key daily), but at the same time it is necessary to keep the files on the previous days on s3 and not delete they.

[AlexAkulov]

done