Remove ExclusivelyOwned from register_dispatch_key (#106791)
This fixes a bug that could occur with python decompositions.
When an operation is intercepted in the c++ code in pytorch the outputs a created as `ExclusivelyOwned<at::Tensor>`s. Later on when it dispatches back to python for the decomposition these tensors have their ownership shared with python. In a normal use case the exclusively owned tensor is released and it's value returned as a non-exclusively owned tensor from the operation. However if the python decomposition throws an error the `ExclusivelyOwned` wrapper destroys the `at::Tensor` leading to a python reference to a tensor which isn't alive (and meaning pytorch falls over in debug mode).
Note this will be a performance hit when handling errors.
Fixes #106790
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106791
Approved by: https://github.com/ezyang
