**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.

{
    if (!is_leader)
        return;
    const auto storage_settings_ptr = getSettings();
    const bool deduplicate = false; 
    const Names deduplicate_by_columns = {};
    CreateMergeEntryResult create_result = CreateMergeEntryResult::Other;
    try
    {
        
        
        std::lock_guard merge_selecting_lock(merge_selecting_mutex);
        auto zookeeper = getZooKeeper();
        ReplicatedMergeTreeMergePredicate merge_pred = queue.getMergePredicate(zookeeper);
        
        
        
        auto merges_and_mutations_queued = queue.countMergesAndPartMutations();
        size_t merges_and_mutations_sum = merges_and_mutations_queued.merges + merges_and_mutations_queued.mutations;
        if (merges_and_mutations_sum >= storage_settings_ptr->max_replicated_merges_in_queue)
        {
            LOG_TRACE(log, "Number of queued merges ({}) and part mutations ({})"
                " is greater than max_replicated_merges_in_queue ({}), so won't select new parts to merge or mutate.",
                merges_and_mutations_queued.merges,
                merges_and_mutations_queued.mutations,
                storage_settings_ptr->max_replicated_merges_in_queue);
        }
        else
        {
            UInt64 max_source_parts_size_for_merge = merger_mutator.getMaxSourcePartsSizeForMerge(