Updating a Nullable column value by using alter .... where ... causes to set another value!

ClickHouse version: 20.6.3.28
Engine: MergeTree
OS: Ubuntu 18.04.3 LTS

Steps to reproduce:
```sql
CREATE TABLE table1(
	id int,
	price Nullable(Int32)
)
ENGINE = MergeTree()
PARTITION BY id
ORDER BY (id);
INSERT INTO table1 (id, price) VALUES (1, 100);
ALTER TABLE table1  update price = 150 where id=1;
SELECT * FROM table1;
```
We expect the price to be `150`, but it's `93148480`:

```
┌─id─┬────price─┐
│  1 │ 93148480 │
└────┴──────────┘
```
Using `Decimal(9,2)` field instead of `Int32` would set the value  `932342.88` always. It seems there's a fixed value for each data type.

If we don't use such a `where` clause, it works correctly:
```sql
ALTER TABLE db1.table1  update price = 150 where 1=1;
┌─id─┬─price─┐
│  1 │   150 │
└────┴───────┘
```
#pragma once
#include <cmath>
#include <Columns/IColumn.h>
#include <Columns/IColumnImpl.h>
#include <Columns/ColumnVectorHelper.h>
#include <common/unaligned.h>
#include <Core/Field.h>
#include <Core/BigInt.h>
namespace DB
{
/** Stuff for comparing numbers.
  * Integer values are compared as usual.
  * Floating-point numbers are compared this way that NaNs always end up at the end
  *  (if you don't do this, the sort would not work at all).
  */
template <class T, class U = T>
struct CompareHelper
{
    static constexpr bool less(T a, U b, int ) { return a < b; }