…139541)

This is tested in PR stacked above in

```python
python test/distributed/fsdp/test_fsdp_state_dict.py TestFSDPStateDict.test_torch_save_load
```

We cannot depend on whether `hasattr(..., __slots__)` to know whether a BUILD instruction has slotstate. For example, if a class subclasses ABC `hasattr(__slots__)` will be `True` but there might be no slots (and hence `state` will not be a tuple). So revert #138936 to following the pickle library's code

```python

>>> from abc import ABC
>>> hasattr(ABC, "__slots__")
True
```

So

```python
import torch
from abc import ABC
from dataclasses import dataclass

class Foo(ABC):
    pass

class FooWrapper(Foo):
    def __init__(self, x, y):
        self.x = x
        self.y = y

f = FooWrapper(1, 2)
torch.save(f, "temp.pt")
with torch.serialization.safe_globals([FooWrapper]):
    torch.load("temp.pt")
```

Would fail on the previous code with
```
File "/data/users/mg1998/pytorch/torch/serialization.py", line 1934, in _load
    result = unpickler.load()
  File "/data/users/mg1998/pytorch/torch/_weights_only_unpickler.py", line 366, in load
    for k, v in slotstate.items():
```

As there is actually no slotstate

Pull Request resolved: #139541
Approved by: https://github.com/malfet
ghstack dependencies: #138936, #139221, #139433

Pull Request resolved: #137602
Approved by: https://github.com/malfet, https://github.com/albanD
ghstack dependencies: #138936, #139221, #139433, #139541

Prevent same global from being added multiple times

Pull Request resolved: #139303
Approved by: https://github.com/janeyx99
ghstack dependencies: #138936, #139221, #139433, #139541, #137602

Pull Request resolved: pytorch#139433
Approved by: https://github.com/malfet
ghstack dependencies: pytorch#138936, pytorch#139221