**Describe the bug**
The ClickHouse client freezes when executing `ALTER TABLE` with `ADD COLUMN` and `MODIFY ORDER` on a table built using Replicated Versioned Collapsing Merge Tree engine.

**How to reproduce**
* ClickHouse client version 20.10.1.1.
Connecting to localhost:9000 as user default.
Connected to ClickHouse server version 20.10.1 revision 54440.

* `CREATE TABLE` statements
```
SHOW CREATE TABLE table0

┌─statement──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ CREATE TABLE default.table0
(
    `d` Date,
    `a` String,
    `b` UInt8,
    `x` String,
    `y` Int8,
    `version` UInt64,
    `sign` Int8 DEFAULT 1
)
ENGINE = ReplicatedVersionedCollapsingMergeTree('/clickhouse/tables/{shard}/table0', '{replica}', sign, version)
PARTITION BY y
ORDER BY d
SETTINGS index_granularity = 8192 │
└────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

1 rows in set. Elapsed: 0.004 sec.
```

* Queries to run that lead to unexpected result
```
ALTER TABLE table0 ADD COLUMN order UInt32, MODIFY ORDER BY (d, order)
```
if (metadata_diff.constraints_changed)
            new_metadata.constraints = ConstraintsDescription::parse(metadata_diff.new_constraints);
        if (metadata_diff.ttl_table_changed)
        {
            if (!metadata_diff.new_ttl_table.empty())
            {
                ParserTTLExpressionList parser;
                auto ttl_for_table_ast = parseQuery(parser, metadata_diff.new_ttl_table, 0, DBMS_DEFAULT_MAX_PARSER_DEPTH);
                new_metadata.table_ttl = TTLTableDescription::getTTLForTableFromAST(
                    ttl_for_table_ast, new_metadata.columns, global_context, new_metadata.primary_key);
            }
            else 
            {
                new_metadata.table_ttl = TTLTableDescription{};
            }
        }
    }
    
    
    checkTTLExpressions(new_metadata, old_metadata);
    setProperties(new_metadata, old_metadata);
    auto table_id = getStorageID();
    DatabaseCatalog::instance().getDatabase(table_id.database_name)->alterTable(global_context, table_id, new_metadata);
}
/** If necessary, restore a part, replica itself adds a record for its receipt.
  * What time should I put for this entry in the queue? Time is taken into account when calculating lag of replica.
  * For these purposes, it makes sense to use creation time of missing part
  *  (that is, in calculating lag, it will be taken into account how old is the part we need to recover).
  */
static time_t tryGetPartCreateTime(zkutil::ZooKeeperPtr & zookeeper, const String & replica_path, const String & part_name)