**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.

else
    {
        
        return 0;
    }
}
void StorageReplicatedMergeTree::getReplicaDelays(time_t & out_absolute_delay, time_t & out_relative_delay)
{
    assertNotReadonly();
    time_t current_time = time(nullptr);
    out_absolute_delay = getAbsoluteDelay();
    out_relative_delay = 0;
    const auto storage_settings_ptr = getSettings();
    /** Relative delay is the maximum difference of absolute delay from any other replica,
      *  (if this replica lags behind any other live replica, or zero, otherwise).
      * Calculated only if the absolute delay is large enough.
      */
    if (out_absolute_delay < static_cast<time_t>(storage_settings_ptr->min_relative_delay_to_measure))
        return;
    auto zookeeper = getZooKeeper();
    time_t max_replicas_unprocessed_insert_time = 0;
    bool have_replica_with_nothing_unprocessed = false;
    Strings replicas = zookeeper->getChildren(fs::path(zookeeper_path) / "replicas");
    for (const auto & replica : replicas)
    {
        if (replica == replica_name)
            continue;
        
        if (!zookeeper->exists(fs::path(zookeeper_path) / "replicas" / replica / "is_active"))
            continue;