fix TensorLikePair origination (#70304)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70304
Without this patch `TensorLikePair` will try to instantiate everything although it should only do so for tensor-likes. This is problematic if it is used before a different pair that would be able to handle the inputs but never gets to do so, because `TensorLikePair` bails out before.
```python
from torch.testing._comparison import assert_equal, TensorLikePair, ObjectPair
assert_equal("a", "a", pair_types=(TensorLikePair, ObjectPair))
```
```
ValueError: Constructing a tensor from <class 'str'> failed with
new(): invalid data type 'str'.
```
Test Plan: Imported from OSS
Reviewed By: ngimel
Differential Revision: D33542995
Pulled By: mruberry
fbshipit-source-id: 77a5cc0abad44356c3ec64c7ec46e84d166ab2dd
