Looks like https://github.com/ClickHouse/ClickHouse/pull/21303 is broke also "clear column" for such columns.

How to reproduce:

```
CREATE TABLE test.TTAdmLog
(
    `ts` DateTime,
    `event_date` Date DEFAULT toDate(ts),
    `impression_id` String DEFAULT '',
    `creative_id` String DEFAULT '',
    `creative_adm` String DEFAULT '',
    `impression_id_compressed` FixedString(16) DEFAULT UUIDStringToNum(impression_id),
    `impression_id_hashed` UInt16 DEFAULT reinterpretAsUInt16(impression_id_compressed),
)
ENGINE = ReplicatedMergeTree('/clickhouse/tables/{shard}/TTAdmLogTest', '{replica}')
PARTITION BY toMonday(event_date)
ORDER BY (event_date, impression_id_hashed)
SAMPLE BY impression_id_hashed
SETTINGS replicated_deduplication_window = 1000, replicated_deduplication_window_seconds = 864000, index_granularity = 8192

CREATE MATERIALIZED VIEW test.TTView
(
    `event_date` Date,
    `creative_id` String,
    `creative_adm` AggregateFunction(anyLast, String),
)
ENGINE = ReplicatedAggregatingMergeTree('/clickhouse/tables/{shard}/TTViewTest', '{replica}', event_date, (event_date, creative_id), 8192) AS
SELECT 
    toStartOfMonth(event_date) AS event_date,
    arrayJoin(splitByChar(',', creative_id)) AS creative_id,
    anyLastState(creative_adm) AS creative_adm,
FROM test.TTAdmLog
GROUP BY 
    event_date,
    creative_id,

```


ClickHouse server version 20.9.3 revision 54439.

```
alter table test.TTAdmLog clear column creative_adm in partition '2021-03-22'

OK

```
ClickHouse server version 21.4.3 revision 54447.

```
alter table test.TTAdmLog  clear column creative_adm in partition '2021-03-22'

DB::Exception: Trying to ALTER DROP column creative_adm which is referenced by materialized view ['TTView'].

```

CurrentMetrics::sub(CurrentMetrics::StorageBufferBytes, block_to_write.bytes());
    ProfileEvents::increment(ProfileEvents::StorageBufferFlush);
    if (!destination_id)
    {
        LOG_DEBUG(log, "Flushing buffer with {} rows (discarded), {} bytes, age {} seconds {}.", rows, bytes, time_passed, (check_thresholds ? "(bg)" : "(direct)"));
        return;
    }
    /** For simplicity, buffer is locked during write.
        * We could unlock buffer temporary, but it would lead to too many difficulties:
        * - data, that is written, will not be visible for SELECTs;
        * - new data could be appended to buffer, and in case of exception, we must merge it with old data, that has not been written;
        * - this could lead to infinite memory growth.
        */
    Stopwatch watch;
    try
    {
        writeBlockToDestination(block_to_write, DatabaseCatalog::instance().tryGetTable(destination_id, getContext()));
        if (reset_block_structure)
            buffer.data.clear();
    }
    catch (...)
    {
        ProfileEvents::increment(ProfileEvents::StorageBufferErrorOnFlush);
        
        CurrentMetrics::add(CurrentMetrics::StorageBufferRows, block_to_write.rows());
        CurrentMetrics::add(CurrentMetrics::StorageBufferBytes, block_to_write.bytes());
        buffer.data.swap(block_to_write);
        if (!buffer.first_write_time)
            buffer.first_write_time = current_time;