Allow restore keeper data from old format where Value is String #1238
Description
To avoid error
2025-09-13 08:07:05.606 ERR pkg/backup/restore.go:576 > can't /var/lib/clickhouse/backup/shard1-20250912161019/access/replicated.jsonl json.Unmarshal error: {"path":"uuid/174f3a9a-828f-e325-aa95-65213baf5a81","value":"ATTACH USER xxx IDENTIFIED WITH sha256_hash BY ...\n"} line: illegal base64 data at input byte 6