**Describe the situation**

When using parameters (`param`) in the CLI or with the HTTP interface, the EmbeddedRocksDB engine will scan through all the data causing significant slowdown, instead of doing a proper RocksDB key lookup.

**How to reproduce**

setup.sql:
```sql
CREATE TABLE test1 (key String, value String) ENGINE=EmbeddedRocksDB PRIMARY KEY key;

-- do this a few times to exacerbate the issue
INSERT INTO test1 (*) SELECT n.number, randomString(10000) FROM numbers(10000) n;
INSERT INTO test1 (*) SELECT n.number, randomString(10000) FROM numbers(10000) n;
INSERT INTO test1 (*) SELECT n.number, randomString(10000) FROM numbers(10000) n;
```

```
❯ clickhouse client "--param_key=5000" --query "SELECT value FROM test1 WHERE key = {key:String} FORMAT JSON" | jq ".statistics"
{
  "elapsed": 0.20763,
  "rows_read": 10000,
  "bytes_read": 100218890
}

❯ clickhouse client --query "SELECT value FROM test1 WHERE key = '5000' FORMAT JSON" | jq ".statistics"
{
  "elapsed": 0.000519,
  "rows_read": 1,
  "bytes_read": 10022
}
```

**Version**
22.6.1.231


const StorageEmbeddedRocksDB & storage_,
        const Block & header,
        FieldVectorPtr keys_,
        FieldVector::const_iterator begin_,
        FieldVector::const_iterator end_,
        const size_t max_block_size_)
        : ISource(header)
        , storage(storage_)
        , primary_key_pos(getPrimaryKeyPos(header, storage.getPrimaryKey()))
        , keys(keys_)
        , begin(begin_)
        , end(end_)
        , it(begin)
        , max_block_size(max_block_size_)
    {
    }
    EmbeddedRocksDBSource(
        const StorageEmbeddedRocksDB & storage_,
        const Block & header,
        std::unique_ptr<rocksdb::Iterator> iterator_,
        const size_t max_block_size_)
        : ISource(header)
        , storage(storage_)
        , primary_key_pos(getPrimaryKeyPos(header, storage.getPrimaryKey()))
        , iterator(std::move(iterator_))
        , max_block_size(max_block_size_)
    {
    }
    String getName() const override { return storage.getName(); }