**How to reproduce**
Clickhouse version 20.11.5.18, 20.8.7.15, 20.3.19
```
SELECT
    groupUniqArray(val) AS uniq,
    toTypeName(uniq),
    groupArray(val) AS arr,
    toTypeName(arr)
FROM
(
    SELECT CAST(number % 2, 'Enum(\'hello\' = 1, \'world\' = 0)') AS val
    FROM numbers(2)
)

Query id: d4657f27-c8bd-4174-9947-c6c48d0222d5

┌─uniq──┬─toTypeName(groupUniqArray(val))─┬─arr───────────────┬─toTypeName(groupArray(val))────────────┐
│ [0,1] │ Array(Int8)                     │ ['world','hello'] │ Array(Enum8('world' = 0, 'hello' = 1)) │
└───────┴─────────────────────────────────┴───────────────────┴────────────────────────────────────────┘
```

{
        UInt64 elems;
        readVarUInt(elems, buf);
        if (unlikely(elems == 0))
            return;
        if (unlikely(elems > AGGREGATE_FUNCTION_GROUP_ARRAY_MAX_ARRAY_SIZE))
            throw Exception("Too large array size", ErrorCodes::TOO_LARGE_ARRAY_SIZE);
        if (limit_num_elems && unlikely(elems > max_elems))
            throw Exception("Too large array size, it should not exceed " + toString(max_elems), ErrorCodes::TOO_LARGE_ARRAY_SIZE);
        auto & value = data(place).value;
        value.resize(elems, arena);
        for (UInt64 i = 0; i < elems; ++i)
            value[i] = Node::read(buf, arena);
        if constexpr (Trait::sampler == Sampler::RNG)
        {
            DB::readIntBinary<size_t>(data(place).total_values, buf);
            std::string rng_string;
            DB::readStringBinary(rng_string, buf);
            ReadBufferFromString rng_buf(rng_string);
            rng_buf >> data(place).rng;
        }
        
        
    }
    void insertResultInto(AggregateDataPtr place, IColumn & to, Arena *) const override