**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.

{
    auto lock = getLock();
    return shared->users_config;
}
void Context::setUser(const UUID & user_id_)
{
    auto lock = getLock();
    user_id = user_id_;
    access = getAccessControlManager().getContextAccess(
        user_id_,  {},  true, settings, current_database, client_info);
    auto user = access->getUser();
    current_roles = std::make_shared<std::vector<UUID>>(user->granted_roles.findGranted(user->default_roles));
    auto default_profile_info = access->getDefaultProfileInfo();
    settings_constraints_and_current_profiles = default_profile_info->getConstraintsAndProfileIDs();
    applySettingsChanges(default_profile_info->settings);
    if (!user->default_database.empty())
        setCurrentDatabase(user->default_database);
}
std::shared_ptr<const User> Context::getUser() const
{
    return getAccess()->getUser();
}
String Context::getUserName() const
{
    return getAccess()->getUserName();
}
std::optional<UUID> Context::getUserID() const