**Describe the issue**
ClickHouse is unable to start up after upgrading from 20.8 to 21.8. 

There is a replicated table with `:` in zk path and it couldn't be loaded with:

`2021.09.15 03:49:58.435071 [ 633075 ] {} <Error> Application: DB::Exception: Unknown auxiliary ZooKeeper name '/test_prefix'. If it's required it can be added to the section <auxiliary_zookeepers> in config.xml: Cannot attach table `db1`.`table1` from metadata file /var/lib/clickhouse/metadata/db1/table1.sql from query ATTACH TABLE db1.table1 (`field1` String, `date` Date) ENGINE = ReplicatedMergeTree('/test_prefix:db1/{shard}/table1', '{replica}') PARTITION BY toMonth(date) PRIMARY KEY field1 ORDER BY field1 SETTINGS index_granularity = 8192: while loading database `db1` from path /var/lib/clickhouse/metadata/db1
`

**Expected behavior**
ClickHouse server is able to startup after upgrade without schema change. "test_prefix" in "/test_prefix:db1/{shard}/table1" is not interpreted as an auxiliary ZooKeeper name.

|| MergeTreePartInfo::contains(part_on_replica, largest_part_found, format_version))
                {
                    largest_part_found = part_on_replica;
                }
            }
        }
        if (!largest_part_found.empty())
        {
            bool the_same_part = largest_part_found == entry.new_part_name;
            
            if (!the_same_part)
            {
                String reject_reason;
                if (!queue.addFuturePartIfNotCoveredByThem(largest_part_found, entry, reject_reason))
                {
                    LOG_INFO(log, "Will not fetch part {} covering {}. {}", largest_part_found, entry.new_part_name, reject_reason);
                    return {};
                }
            }
            return replica;
        }
    }
    return {};
}
String StorageReplicatedMergeTree::findReplicaHavingCoveringPart(
    const String & part_name, bool active, String & found_part_name)
{
    auto zookeeper = getZooKeeper();
    Strings replicas = zookeeper->getChildren(fs::path(zookeeper_path) / "replicas");