**Describe the situation**
multiIf works 10 times slower than If with single condition.

**How to reproduce**
ClickHouse version 21.10

```

SELECT count()
FROM numbers_mt(1000000000)
WHERE NOT ignore(multiIf(number = 0, NULL, toNullable(number)))

┌────count()─┐
│ 1000000000 │
└────────────┘

1 rows in set. Elapsed: 10.267 sec. Processed 1.00 billion rows, 8.00 GB (97.41 million rows/s., 779.25 MB/s.)

SELECT count()
FROM numbers_mt(1000000000)
WHERE NOT ignore(If(number = 0, NULL, toNullable(number)))

┌────count()─┐
│ 1000000000 │
└────────────┘

1 rows in set. Elapsed: 1.010 sec. Processed 1.00 billion rows, 8.00 GB (990.63 million rows/s., 7.93 GB/s.)
```

**Expected performance**
The same performance for multiIf and if.

{
    ConvertFunctionOrLikeVisitor::Data data = {};
    ConvertFunctionOrLikeVisitor(data).visit(query);
}
}
void TreeOptimizer::optimizeIf(ASTPtr & query, Aliases & aliases, bool if_chain_to_multiif)
{
    
    OptimizeIfWithConstantConditionVisitor(aliases).visit(query);
    if (if_chain_to_multiif)
        OptimizeIfChainsVisitor().visit(query);
}
void TreeOptimizer::optimizeCountConstantAndSumOne(ASTPtr & query)