Switch default memory format of to (and similar) operators to Preserve
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/30088
Test Plan: Imported from OSS
Differential Revision: D18624984
Pulled By: VitalyFedyunin
fbshipit-source-id: 54901786d7496c7dce785140b0585ac9093b1d86
