**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.

const DataPartPtr & part, Coordination::Requests & ops, String part_name, NameSet * absent_replicas_paths)
{
    if (part_name.empty())
        part_name = part->name;
    auto local_part_header = ReplicatedMergeTreePartHeader::fromColumnsAndChecksums(
        part->getColumns(), part->checksums);
    Strings replicas = zookeeper->getChildren(fs::path(zookeeper_path) / "replicas");
    std::shuffle(replicas.begin(), replicas.end(), thread_local_rng);
    bool has_been_already_added = false;
    for (const String & replica : replicas)
    {
        String current_part_path = fs::path(zookeeper_path) / "replicas" / replica / "parts" / part_name;
        String part_zk_str;
        if (!zookeeper->tryGet(current_part_path, part_zk_str))
        {
            if (absent_replicas_paths)
                absent_replicas_paths->emplace(current_part_path);
            continue;
        }
        ReplicatedMergeTreePartHeader replica_part_header;
        if (part_zk_str.empty())
        {
            String columns_str;
            String checksums_str;
            if (zookeeper->tryGet(fs::path(current_part_path) / "columns", columns_str) &&
                zookeeper->tryGet(fs::path(current_part_path) / "checksums", checksums_str))
            {
                replica_part_header = ReplicatedMergeTreePartHeader::fromColumnsAndChecksumsZNodes(columns_str, checksums_str);