Fix caffe2 windows CI for new Windows AMI (#21452)
Summary:
The alternative of #21410.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21452
Differential Revision: D15701767
Pulled By: ezyang
fbshipit-source-id: e65c1d6bfcc98e88460f4a57e5b99c2f395c0ceb
