`is_subclass_of` is true only for parent classes, not the same one

# Bug report

`is_subclass_of(new A(), A::class)` is false, phpstan assumes true

### Code snippet that reproduces the problem

https://3v4l.org/Z4Yb2

https://phpstan.org/r/b41d286a-72cb-45a7-b48f-5dbedc4dee73

### Expected output

`Call to function is_subclass_of() with B and 'A' will always evaluate to true.` only