[Validator] Sequence constraint can not be applied onto class as an attribute

### Symfony version(s) affected

5.4 \ 6.0

### Description

Sequence constraint can not be applied onto class as an attribute.

### How to reproduce

```
<?php

#[Assert\Sequence([
    new NotBlank()
])]
class SomeClass {
}
```

### Possible Solution

_No response_

### Additional Context

More details in PR: https://github.com/symfony/symfony/pull/44448