Revert D24667128: [c10d] switch Store to be managed by intrusive_ptr
Test Plan: revert-hammer
Differential Revision:
D24667128 (https://github.com/pytorch/pytorch/commit/0cfe3451d485f9e1ac2828cc2dd53d331f61ce24)
Original commit changeset: 9b6024c31c85
fbshipit-source-id: d8ddf9eb2fccef5023e05698e0c4662708fe4945
