Turn on memory efficient format for jit pickle files.
Summary:
This enables previous change made at D35196883 (https://github.com/pytorch/pytorch/commit/b34b192d6b97325c9f78e5995c48c8498ede34bd)
Previous change is landed for 2 weeks to make sure that the format change introduced here will be handed in code.
Test Plan: existing tests
Differential Revision: D36074453
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76688
Approved by: https://github.com/gmagogsfm
